Talking about Epic 4g specifically (which is a Galaxy S phone) - I updated to Sprint test release of 2.2 (DK28), converted to EXT4 from the absolutely horrific RFS and then updated to Quantum ROM. It is a lot better - lags gone, battery life improved a lot, and to your question - I also have the stock Epic UX with TouchWiz. If you want all the Sprint apps along with TW UX - There is another ROM that was recently updated - TrulyEpic 1.2.

But Samsung sucks - I am not going to buy anything they sell - even ignoring all of the rumors they have badly botched up by not updating to 2.2 for all of their US Galaxy phones for so long.