I've been very disappointed the battery usage on my new sp4. I'm using a reading app (Freda) and have the unit settings a the darker option and the battery saver on with the reading app light setting at about 50% and can only read for 3 to 4 hours before the unit needs to be recharged. I talked with tech support and the decided to send me a new unit but this one is no better on battery drain than the first. I was really hoping for a 9 to 10 charge at the very least. This actual reading time from 100% to 8% battery scale. using the sp4 i5
Battery life varies with both usage and what you have running in the background. I'm still early in my testing but, once I disabled all cloud synchronization programs that I had running (OneDrive, Cubby), I'm up to 8'ish hours of projected battery life (21% over 105 minutes), up from about 6.5 hours when all I do is use Chrome with Adblock. I think most people have a lot of things installed that run in the background that they're not aware of or are browsing sites with a lot of ads that chew up a lot of CPU cycles. You can find my battery life tracking here: Tracking Battery Life
I still prefer the smaller screen, for increased portability.
In all honesty, my SP2 is plenty powerful enough for me, but I'm often hitting the limits of my 4GB RAM limit, so if I'm gonna upgrade, 8GB is mandatory.
Computing power is very important to me, but since this is primarily a mobile platform, battery life is everything. If the i7 gets an hour or more less life off of a charge than the i5 would, then I'd probably rather have the i5.
Id recommend getting the 8 GB SP2. Not only because its your ideal size (size matters, a lot), but its also a lot cheaper by now, although you may need to buy used. The second candidate would be the 8 GB SP4, but you lose the Power Cover, size preference, and cost advantage.
If you prefer Windows 8.1, the SP4 is also pretty much a no-go.
True but if you're web browsing and that's what it is telling you, and you continue to do that for the next hour, the time remaining should be right. But again, depends on web pages with ads or how often you stop and read, etc.
Just as a heads up, pay absolutely no attention to the time remaining figure under battery. Their algorithms are completely fubared. If you run you system hard to 2 minutes Windows decides that this is how the machine will be used til it is empty and so just tells you 3 hours left. 5 minutes later it'll tell you 10 hours. It really is meaningless.