So it has been a few days now with the 3500 battery. I am happy with it so far. It sure doesnt feel like it is actually 3500mah, but maybe 2x more than stock.
The cover fits fine, I have had no trouble with that at all. In my search for never ending battery life I downloaded statup auditor and screen filter to see if that helps.
If you are on the fence, for less than $15 it is worth it. I got 26 hours out of it the first time and and just starting my second round with it. To condition the phone I charged til green while on, turned off and charged til green again, turn on turn off and charge til green again, boot into CW3 and wipe battery stats and restart. That seems to help a little.