Anyone try this battery, i heard you have to change the back cover of the phone but it has amazing performance. Please advise...
I had the Seidio extended battery (1750mah) in my EVO before I returned it. It added a bit extra life to the phone and no complaints with it.
For my Nexus One, I had the Seidio 2800mah extended battery, which like the one you're looking at, is oversized and requires a replacement back to the phone from Seidio. I was very disappointed with it. It was ugly, didn't fit snugly, and felt cheap. I can't say that the EVO line is the same, but my track record with the company is that the batteries are great, but the cases are poor replacements for the stock one, but they'll do for you if you're not worried about that and need a LOT of extra juice while out and about. I rarely use mine on the Nexus One, I just make sure I have a charger and cable in my car, work, and other places. Dock the phone whenever I have a chance and I rarely run out of juice.
P.S. - here's some pics of my Nexus One with a Seidio battery back on it