At the moment, Android is just for fun. It's a really nice OS, and the work thats being done on this forum is staggering considering its being done by people UNPAID, and IN THERE OWN TIME! Sorry just like to stress that point to people who moan... Huge teams of HTC employees are on 60-70K a year writing code that these guys will probably end up doing a better job of for free, but I digress...
If you want to play around with HTC Sense on Android, which is my current toy, you have to make do without Wifi, GPS, Camera, but I don't experience the huge drop in battery life that everyone else does. Maybe I'm just lucky. If you're patient and wait for everything to load, I'd say that it is actually faster than WinMo. The Clean/Glossy versions have a greater capabilty (you get wifi and such like) and are even faster. Probably best to try that one first. Hope that answers your first two questions.
To the last, we're a long way off a ROM, but if things progress at their current rate I don't see why we can't have one some time before we all retire our Xperia's.
To your thread title, as long as you don't expect too much at this stage and you are willing to accept that this is just a "proof of concept" there's no reason not to try it. All you're loosing is half a GB on storage space on you're SD... And the more people that try it, the quicker bugs can be ironed out, and the major things like camera and GPS can be fixed.