CK & DolfanCole - I've been lurking in this and the Bionic forum for a few weeks now. What do you guys think about the GS2 only having a 1650 mAh battery? I know the Bionic is rumored to have a 1750 mAh battery. thoughts?
Welcome. Since you've lurking in both forums, you've undoubtedly seen both myself and CK in both too. I think CK is just following me around.
As you probably know, there are a lot of issues that contribute to how the battery performs or is able to support the use of the phone. I obviously have no firsthand knowledge of how either will do (particularly since the Bionic hasn't been released). But, some thoughts/issues/suggestions ...
If rumored to be true, the GSII will not have LTE. The LTE radio has apparently been a big draw on the battery, and why many people who have LTE phones look for ways either through the UI or 3rd party app to turn it off when not in use. That'll be a major plus for the GSII in that regard.
The screen is also a big draw on the battery. In this case, the Bionic may be better, particularly if it uses a pentile display (as was rumored with the original Bionic). Even with the higher resolution in the Bionic, by using a pentile display, the true pixel/subpixel count is lower than the GSII, and thus less battery needed to support. Both displays are 4.3-in (unless the 4.5-in Bionic rumor proves true), so for screen size, it's a wash.
The UI/skin also has a big impact. From what I've been able to gather TouchWiz and Blur are not as bad as Sense in this regard. But, both have been upgraded for the GSII and Bionic, respectively. So, it's really anyone's guess as to which one will be better on battery life. However, the more bloat that it has, the worse it'll be.
Both devices will have dual-core CPUs. It's theorized that dual-cores will be better on battery life. But, you need a compatible OS before the benefit can be fully realized. That's expected to come in Ice Cream Sandwich. So, hopefully, the battery capacity on both devices will be better utilized further down the road when the OS is updated. And thus, what may seem like a low or average battery capacity now should (theoretically) only get better.
The same thoughts apply to the RAM memory type. The original Bionic was stated to have DDR2 RAM, which would be better on the battery than the previous standard of DDR. I don't know what the GSII has. I hope its DDR2 as well.
I'd also look through the main GSII forum and see if there's feedback from those that already own the GSII and how their battery life is.
That's all I can think of now. If I think of more, I'll post it.