Just some benchmark results. Not much of a difference.
Quadrant Score. Each benchmark was ran 2 times.
1513 - Chevy ULV 1.2ghz
1563 - P3 ULV 1.2ghz
1546 - P3 Normal Volt 1.25ghz
MFLOPS Scores. Each benchmark ran twice. Thus far the first benchmark run also were the best results. Surprising both P3 kernel ran the same.
17.406 - Chevy ULV 1.2ghz
16.812 - P3 ULV 1.2ghz
16.812 - P3 Normal Volt 1.25ghz
It's pretty obvious from these result that Chevy ULV at 1.2 ghz is faster then P3 at 800mhz. So that conclusion is wrong.
So from my conclusion the best Kernel to run out of the three is P3 ULV 1.2Ghz. No reason to run P3 1.25, same scores, however some may benchmark a little higher then others but i assure you it wont be by much and it WILL drain battery life a little faster.