We bought one about five or six years ago (Cabanon Stratos).
It was very nice, but, the fact that it is a trailer tent limits some of the sites you can visit.
I quite liked it, although felt quite embarrassed tbh because it was very big. DH thought it was one step away from the dark side of caravanning (no offence meant, just not for us). We didn't use the under bed bits apart from to fill them with the empty bags the poles/canvas came in.
So after about 18 months we sold it. We lost about £1k on sale, put it towards a lovely tent and a new trailer.
Our beds were not comfortable, you will need to add something for comfort. It just seemed massive and a lot of faff tbh. Drying it on return from a trip seemed harder than drying our current tent - make sure you have somewhere big enough to dry it.
We use a different tent for weekends (do even now), the bother of possibly having to dry such an enormous tent after a couple of days meant we preferred not to take it.
Obvs everything can be stored inside, but that means that you can't access it to make a cup of tea, start thinking about cooking until the thing is pitched unless you plan ahead.
So, I would say don't do it. 50-60 minutes to pitch and peg. Big to dry, can limit site choice.
But if none of that bothers you then it might work for you. If you planned on 3 weeks a year in France, pitching it once or twice for the whole holiday it would pay for itself in 4 years.
I think ours cost £3.5-4K from memory, lovely, well thought out, etc., but just not for us. There are usually lots of nice examples on eBay, I waited and sold mine around this time of year when you pay more for them. If you buy at the end of the summer they cost less.
Storage too, we used to empty the trailer bit and store it inside a barn but checked it every month or so for damp/mice, etc.. It is still a tent though, rain = damp feeling, cold = cold.