I changed baterry poll on sprint stock rom abuot month ago and noticed much more heat on bottom of the phone -and no any improovment on battery live...so reverted it back.
since that time i did some reading ,and instaled sprint touch pro radio and msr 3.0 rom.This rom has battery poll changed,but i see no heat isues now.Battery runs 1 or 2 days now.Huge improovment.
You can instal radio from internal storage,no need hard reset.Its not so hard to do that for new people like me.