The thing I'm most interested in is more info on Flash running. How does it work in the browser? Other than games, how does video do? Have you tried going to a full flash site and tried navigating?
Assuming Froyo on the X is the same as it was on my hacked Droid, Flash worked well. Most sites with flash worked like you'd expect, some really well, mimicking the desktop, while others where a little clunky. For example, some of the flash adverts came into focus so I had to close them out - wasn't really a big deal most of the time but I can see this being a minor annoyance for some. The good news though, is that most of the browsers had a setting to call up flash on demand. So you'd only click on what you want to see.
Flash videos were either slow and choppy or fast and fluid - it really depended on the site. CNN had choppy videos while MSN's were very smooth - almost desktop like. The flash plugin usually alerted me to videos that weren't mobile friendly though. And even though CNN's were choppy, they were definitely good enough to be viewed regardless.
Battery life did suffer a bit, but not that much and should really be expected. Of course it depends totally on how much flash you're viewing. I know I'm prepared to get a second battery or an extended because I will be using it a lot.
IMO, flash even with all its issues was a great, almost necessary addition to the browsing experience. And I really miss it on the X. So Froyo can't come soon enough. For those who don't think they need it all I have to say is: once you go flash they ain't no going back!