J/K - I know what you mean, but sorry I'm not really sure how much that would correlate into battery usage. The difference is not likely to be very much though as memory probably doesn't draw that much wattage anyway.
How much is the $$ difference between the two kits you are looking at? And is the kit listed as compatible with your board? Some boards or BIOSes may not have a setting for 1.35V, or auto may not adjust that low on some, so be sure it's listed compatible before you decide which to get.