I'm using older, 2200 mah versions (same vendor) and they're wonderful. I Sling my Touch and run a marine navigation app w/gps. They really draw power and the enhanced capacity is a must. At first I resisted the idea of the bulbous back. It meant my holsters wouldn't fit and was just too large. Well, I not only got over it but have found a tremendous benefit. I can set the Touch on it's side (on my computer desk, for example) and the extended back acts as a "kickstand". It doesn't flop over and works great in speakerphone mode. Finally, the finish on the back cover is a PERFECT MATCH in color and texture. I've got three of these battery/case combos and couldn't be happier. BTW- I picked up an M-Rock Biscayne case and the Touch w/battery fits perfectly and provides room for an extra battery (2200/2400), Jabra BT 8040, stereo earbuds (inside flap), and mini usb/3.5mm cord(outside flap).
http://www.m-rock.com/biscayne-30-46.htm