The online manual has the detailed descriptions, I believe. We discussed this a while back when the phone first came out, but basically, you're gonna want to stick to High Performance and then individually turn off any features (auto-sync, background data, GPS, 4G toggle on/off, etc) you don't need in order to save you some juice.
Anything other than High Performance will disable 4G, which I'm sure nobody wants.
That's not true. I have had my phone in Normal mode since its release. I get 4G. I also get my emails pushed to me from Gmail. It will switch to 3G only when I toggle from high to normal or normal to low. But if I leave it in normal and restart the phone, I always get 4G in a 4G area.
I could not find any reference to this in the pdf manual. Please tell me what online manual are you referring too?