Does convertible backpack have to be checked at museums, etc?

That bag looks small enough but It depends on each museum. Check the policy of each before you go.
Churches don't check bags the security may look in the bag or wave a wand over it.

Because of security needs I would suspect that most major museums would require you to check a bag as big as that; but check with the RS staff as to their experience.

Yes, I'll agree it depends on the museum but at that size I might expect them to ask for it to be checked.

I found 2 different museums in Germany that were stricter than museums I had visited in other countries - about my regular cross-body purse.

I use a Le Sportsac Everyday purse that is about 13x8.5. In a museum I went in to in Trier ALL purses and backpacks had to be checked. In the Neue Pinakothek art museum in Munich the guard held up an A4 size piece of paper (I think that is the name of regular paper there??) and altho the binding of my purse was wider than the paper he shrugged and let me take it in.

I've never had the size of that purse (which is a lot smaller than the Veloce or the Sherpani you are looking at) questioned in France, UK or Italy.

My experience in Germany in 2015 was the same as Pam's: I think every museum I visited in Berlin and Dresden (and there were quite a few) required me to check my ordinary-sized cross-body bag. I suspect in Germany, you might as well go with the backpack, because whatever you carry will have to be checked. In other countries, size or configuration may make a difference; I have often been able to carry my purse around with me; a couple of times the water-bottle in the exterior pocket was a no-no.

What cities are you visiting?

I have a little backpack I bought in Brugge that is about the same size. Knowing it can't go into museums, I carry a small, thin, cloth purse inside the backpack to transfer the valuable items into: wallet, tissues, phone. The rest gets checked. You may want to carry something inside the tote/pack just in case--even a plastic bag for your valuables.

Since you want to vary how you carry your items, you may want to look at a Scottevest. I have the 24-pocket black jacket with removable sleeves and love being purse-free. It's so nice that I wear it when I'm not traveling, too.

Security at Notre Dame in Paris may not let you bring that bag inside. They do not allow large bags or backpacks. There is no bag storage room.
They have been pretty strict recently.
I wouldn't assume that all churches allow large bags.

I learned many years ago that I never used most of the stuff I was carrying in my RS Civita daypack or my cross-body Baggalini Hobo tote. I switched to very small Baggallini cross-body purses like this and never looked back. If I need to shop or carry anything extra, I use a recycled mesh bag or just a plastic bag from the store.

So far I've never been required to check anything anywhere, but I have done so out of convenience for me and concern for the objects inside. Keep in mind that a pack on the back can be dangerous for the art in a museum or church. If you wouldn't feel confident wearing or carrying your pack or bag in a small shop with lots of breakable items, don't wear or carry it in a church or museum. FYI, at the Borghese last summer it looked like any bag bigger than my little purse had to be checked.

On the next trip, I'll likely be taking this backpack for my hiking pole or cane. Depending on the weather, it might also have a jacket in it. It will never be stuffed like it is in the picture, but I fully expect to check it in some places.

Thanks everyone. I'm considering the backpack because if I don't buy it now, it will be discontinued when I want it. Just like a good pair of shoes - by the time you realize how much your feet like them, they're discontinued and you can't find another pair. I have a tiny crossbody bag which will fit inside the backpack for essentials if I had to check the backpack.

Acraven: I have no current travel plans but am still hoping to go to Italy. This year and next are US road trips to our 50th high school reunions plus finishing house repairs and redecorating. Only flight will be to Denver when our thieving travel agent goes to trial.

Bets: thanks for the vest idea but I'm not a vest person. I have vests in my closet that were gifts, have never been worn and need to go to Goodwill.

Lo: this is probably old news to you, but according to a TV news report Condor Air will start direct Phoenix to Frankfurt flights in May. I wonder if they'll have a ticket sale to introduce it?

Well, it should comply for the Prado's Museum measurements of 40 cm x 40 cm. That qis just under 16 inches square. Needs to fit through their scanner though.

On our recent trip to Rome, one member of our party carried a small rucksack / backpack. I think most of the museums made him check it. I wore a ScotteVest and carried as much as he did more conveniently. I never had to check it. Security always made him remove and open his backpack which as inconvenient because he used safety pins to secure the zippers. I just unzipped my ScotteVest and held it open for a quick glance.

It was a little warm but not much. I always wore it zipped up or mostly zipped up with the collar down. That way, it kept my interior pockets secure. However, my wife cannot tolerate any heat and she mostly carried her vest. That made it as insecure as a purse.

If you do not mind being a little warmer, try the ScotteVest. I'll use it again.

My experience in Germany was the same. My small baggalini cross-body purse was fine, but we had to check our camera bag, which was not really bigger in height or length, but was wider/thicker.

Thanks everyone. Only follow up question I have is how safe was it to check your camera or did you carry it and just check the bag?

I know same people like vests but I’m not one, I really dislike wearing vests of any kind. What I ended up doing was to buy a small fabric/leather purse at Nordstrom’s Rack that can be worn crossbody and a packable backpack from EddieBauer. A combination of those plus my Pacsafe tote and RS rolling carryon should get me everywhere I want
to go.

It was at the Würzburg Residence and the lockers were near the check-in area. They were actual lockers, not an insecure check-in area, so I think we left the camera there. Whether I feel safe doing so really depends on the situation.

Having just returned from London and Paris, I just want to emphasize the following points already mentioned:

1) It really depends on the museum. I had a small backpack. Some required that it be checked; one did not allow me to check it and did not want me wearing it on my back, but only on the front; many allowed it to be checked but did not require it (I always prefer to check it when possible, since I'm much less encumbered without it). For some places it was x-rayed; for others, I had to open it to be looked through.

2) It can change. I hadn't been to Paris in about 9 years. In the intervening time, they have stepped up security requirements all over town. I had to open my bag for a quick search to get into all kinds of places (not just museums, but sometimes shopping malls too). London didn't have nearly so many security checks - for now.

So, if you bring a bag expecting never having to check it, sooner or later you will be disappointed. And what the situation is for Italy now may not be the situation when you actually get there.