G10 over S2 for THX mode and more flexible consumer level pic controls. There may be other little things as well, but those are the main two I think.
If you are patient, and glue yourself to the internet and forums, I'm pretty certain you can better that G10 price. But, that takes time and effort, and you might make a lot more money working, given that time.
50" may sound big to you, but depending on your distance, you may want to go bigger so that you can even benefit from 1080, which offers more than 6x the resolution of 480.
Oh ok, movies only in a dedicated dark basement area. The V10 or equivalent can bypass 3:2 pulldown, I believe it was with 96hz, which is essentially a must for my own movie viewing.
You might want to consider a projector, given the very particular usage, room, and for almost only night viewing.
Good luck.