I'll admit that i might be reading you wrong, but increasing the minimum frequency is not going to help battery life. It will certainly drain your battery much more quickly.
When I say helping Battery Life,
The Performance with your Phone is Stable by increasing the Min Frequency it runs more efficient and less Draw on your Battery giving additional Life to your Battery but Yes, a Higher Frequency Reading over 800 theirs your Battery Killer...
Not the case for me,
My current Reading with Min is 800 and this phone is working Awesome...it proves to be a Positive Increase in my Battery Life in addition to using Juice Defender Ultimate...My average Increase with my Battery is roughly 1 hour & 33 minutes
For me, I am a Heavy user with my phone...so the average is 12 to 14 Hours...Much less before by 8 to 10 Hours...
Battery Life also depends on what's Under The Hood with Apps, Widgets, Syncing, ETC and Phone Usage