I've got an Orchy 600. We used it for a week in Cornwall last yr when it did almost nothing but tip it down & it was great. It's a little bigger than the 500.
It takes a while to put up as it's a big tent, but I don't think it's any more difficult than other large tents of a similar design.
It's got plenty of living space, sleeping space & room to stash kit.
It's rated as a 6 man, but really for comfort I wouldn't want more than 4 adults in it.
Not sure about the 'blowing down' aspect, but it survived some quite strong winds/storms and never felt unstable.
It's got a full built in groundsheet with bits that unclip so you don't trip over it when you have the doors open. I like the fact that the dome part of it is the living area, where you spend most of your time, and the sloping area towards the back is the sleeping area, although even in there it's still plenty high enough….
This year we bought a large canopy extension for it, but have yet to try that out & we also bought the footprint groundsheet as well just to keep the groundsheet clean & make it quicker to put away.