Any experience with Sleeper train

Why would the OBB Nighjet not be secure? The cabin wall is a wall. Maybe with a big axe you would be able to get through...

Sorry, i amended to ÖBB Nightjet (Sleeping Pod). I refer to the sliding/rolling wall. Please see the video clip link.

are those all trains you expect to use? I don't remember you going to all those places.

Which ones do you actually need to make a decision on?

In looking at Brigitte's posts and responses, I get the sense that she is very afraid of crime in Europe. I assume that coming from Singapore, where crime is basically non-existent, the idea of Europe sounds very scary. This is interesting as Europe is actually a very, very safe place. Crime, especially violent crime, is very rare. As a woman, I walk around alone at night in Vienna all the time and am never afraid. Would I do this in the US, where I come from, absolutely not. But, Brigitte, keep in mind that you should not be afraid. Things here are really very much ok.

The Night Riviera and the Great Western sleeper are the same thing. On both the UK sleepers there is room under the bottom bed for large cases, and also room in the Guards van.
Your original plan was to save money with the Sleepers, on the Caledonian Sleeper you are never going to achieve that, in a berth. The prices are, well, very high.
As you talk about the bag lockers I wonder if you mean in the seated coach of the Cal Sleeper. It doesn't have a good reputation as being somewhere to actually get sleep. So far I have neatly swerved that experience, most recently last Monday. Everything I have heard so far is to avoid the seats if you actually need to function next day. One day (probably next month) I will run out of excuses not to use the seating car.
The seats on the Night Riviera are excellent, I've had a good night's sleep on them several times, and that is dirt cheap. There is an hour at Taunton and almost an hour at Exeter when the train is timed to be stationary, which is helpful.

The OBB sleeping pods are only on a few routes currently.

I very much doubt that anyone can break into the Nightjet minicabins without waking up a lot of people nearby.

You asked about sleepers in general. Okay, I was on one in 1982 and I doubt that is relevant today. I wasnt on another until January of this year when I did a round trip on sleepers. Here is my train (the one up): https://1drv.ms/f/c/c9f4c533eb93d92e/EgvgU6CxNvlKu-23WlY4p7oBlHyUyZ6XllxuAkNtNxsQPQ?e=83ImRF and here is fairly nice youtube video of the entire trip (not my trip): https://youtu.be/m9DpriNJG38?si=xT6TBu3UHji7GZFl

It was an interesting experience. Luggage stored safely under the bed, tea was about 10 cents a cup, the bunk mates were three wonderful ladies. 2 of whom spoke some English. The room was clean. The mattres could have been a lot worse. The bedding was perfectly clean. The sleep was a little like trying to sleep in a 1970's style waterbed in an earthquake. I wasnt worried about theft, me and the three ladies could take on anyone. A little worried though about things falling on the train.

Would i use it again? Sure, maybe in the Fall. Was under $100 each way.

are those all trains you expect to use? I don't remember you going to
all those places. Which ones do you actually need to make a decision
on?

I said i ask for their experiences to be shared so that I might make a decision based on your experiences or recommendation.

I won't take OBB Nightjet Sleeper pod due to watching that link. How to store my luggage inside the sleeper pod? Seems that there is not much space for luggage to be kept. The sliding wall seems easy to break into. Please watch this clip.

This is interesting as Europe is actually a very, very safe place.
Crime, especially violent crime, is very rare.

I hope please don't focus on my hometown. I don't intend my hometown as a focus of attention. I prefer my travel plans to be a focus so that i can get clear idea.

Last time, upon my arrival in London, I waited to collect my luggage and was surprised to see that particular luggage wrapped tightly in plastic cling wrap. 1st time to see that.

Yes, London is generally safe which surprised me. I read that other travel book that say that London is a very safe place with low crime rate. I read RS travel book that Frankfurt may not be safe especially at night because of the presence of druggies. I'm very worried that there might be strikes and protests in London and other parts of Europe which may disrupt my travel plans. Stay vigilant is wiser because the tourist may not be familiar how to go to the police station overseas. Prevention is better than cure.

I read that Brussels Midi may not be safe because of muggings and stabbings. Very scary.

Brigitte07 - the likelihood that you will be involved in violent crime is basically 0%. I encourage you to stop reading crazy news stories and try to enjoy your trip or maybe decide that it is best for you just to stay at home.

My experience on a sleeper train was that we got zero sleep. It was uncomfortable, loud and the WC was at the end of the car.
Honestly, when you spend money to go to a new country, it is nice to stay awake on the trains to see the country side. A nice, budget hotel will give you a good nights sleep and cost less than the sleeper train.

As to crime in Frankfurt, we have already told you that you do not have to get off your train at the main station, you will never see the junkies there if you don't want to. Besides that, they don't bother anyone. They sure have never bothered me and I am an older woman. I walk through that area almost daily. All of the main train station areas in Europe look like this. Frankfurt is not the only one.

There is beautiful scenery all over Europe. Spending a ton of money to go to one more country to see one bridge? The Charles bridge is packed with tourists, so it will never look like that tour guide photo.

“ read that Brussels Midi may not be safe because of muggings and stabbings. Very scary.”

I suggest you to find other sources of information. Brussels Midi station isn’t scary. Tens of thousands of passengers travel thru this station on a daily basis without getting mugged or stabbed.
I’m the first one to admit that the immediate area around the Brussels Midi train station isn’t the most attractive. However if you plan to stay in Brussels you can just as easily use Brussels central station which is close to the historical city center.