I've never used a LeCroy ever, but I wouldn't mind having a go to see what they're like.
The problem I had with the 54500 was mainly that I was under the gun to get something fixed, I was working in Noordwijk at ESA's ESTEC R&D facility and was working on some BER measurements on a satellite downlink that was being integrated in the clean room. Being presented with this scope wasn't great, I had to spend valuable time figuring out how to drive it. I am sure if I had had time things would have been better, but we were very time constrained due to project pressures and others wanting to test their bits and pieces too. I have a dear old HP 1980b that is a "one-arm" scope here in the lab for a bit of retro, I used to yearn after this scope back in the day when it was a couple of years' salary. I quite like it now, but it did take quite a while to get used to that UI.
Boot time to me is pretty important, even though it might not be on top of your list. For almost everything I do (mixed signal embedded with RF) I just don't need better than 1 or 2% accuracy on Vp-p and whatnot, it's seeing if a signal's there or not. Timebase-wise, it's not like we're on free-running oscillators anymore, they're all quartz based (at least). If I need an accurate frequency measurement, any better than about 1000ppm, I generally wouldn't be using a scope to do it anyway. I can't imagine having to start work in the morning and have to wait half an hour to do anything. Seriously speaking, do you really regularly and studiously wait 10 minutes to half an hour before using a scope for it to warm up? In edge cases possibly, but in general, no. Happy to be corrected, but this is largely a hangover from the analogue days.
The 54622/41/42 series boot up in less time than it takes you to hook up the probe, so it's pretty convenient for your workflow. Having to sit around while your mind inevitably wonders onto other things simply isn't the best way of working for me.
I agree that Windows isn't the best UI for a scope a lot of the time, but there are some benefits, mostly that extracting data directly, or even fiddling with the data directly on the scope, can be pretty convenient.
The biggest screen I have used for a scope is 8.5", although obviously these days there are bigger, particularly in the five figure scope department.