Oh gosh. Been there, done that. My husband and I (I was 50, hubby was 60, and in good condition) travelled with the RS convertible carry-on for a couple of trips, and then, after running through too many huge airports to meet tight connections, We were done with carrying all the weight on our backs. We opted to buy the Samsonite wheels, and we used those for two trips. They were ok, but definitely not optimal. Their wheel base is very narrow, so the bag had a tendency to tip over frequently. Also, they are cumbersome going through security, and if you store them, folded up, in the long, thin exterior pocket, you're negating some of the space benefit you got from getting a non-wheeled bag.
So, we just went through the process of replacing them with the RS "rolling carry on" bag, and matching "Euro Tote" as the "personal item". I haven't used it yet, but my sister borrowed mine for a carry-on-only trip to Europe, and she raved about how great it was (and she, too, has used several bag types for carry-on travel).
I do not find wheeled types to be disadvantageous over the backpack type. I can run through airports faster with wheels (and with far less fatigue); I don't have to worry about "if I should happen to have a sore back from a poor flight, etc"; you won't wear it going onto public transit anyway (it's too intrusive to have a big pack on your back in such close confines with other people). And I find you really do very little rolling on actual cobblestone sidewalks... MOST are cement, and you can actually carry it by the handle if necessary, and up and down stairs.
But, to answer your question, we decided that using the Samsonite wheels were better than not using them. But, ultimately, we were not happy with the limitations that THEY presented.