I wasn't having any issues and was only hoping for longer battery life. It is way too early to tell but I do feel like it is better on this "1 cycle" so far! I hate to even mention that since there is such a little sample, but tonight it has definitely held it's charge better than it normally has.
"Battery life" is always hard to determine, as conditions tend to vary among discharge cycles. Variability notwithstanding I'm curious about what you are observing re: your old and new SP2.
The original SP2 I had, even after the 12-10 FW messup, still did pretty well, with 9, maybe 10 hours seeming to be typical. When I was running a more demanding mix of apps and services, run-times were indeed shorter.
Now I have the replacement (4300u) SP2 for all of 3 days, so not yet a lengthy track record. However, yesterday the computer ran for ~ 11 hr from full charge to 9% remaining. There were some idle periods, so absolutely nothing systematic or reliable about the result. Even so, considering the SP2's computing power, that result is not too shabby. I'll have to see how it holds up in the weeks ahead.