Mugen is crap, get the cheapest battery you can find on ebay and use it as a backup. Check my sig out for the reviews on common android batteries (Note: The Touch Pro 2 uses the same battery as the Hero)
Either get OEM, or get the cheapest 1500mah replica you can, Mugens and Seidio are super ripoffs
OEM 1500mAh: $11.99
http://cgi.ebay.com/New-OEM-HTC-Touc...item3a59366a5d
OEM 1500mAh almost new: $7.28
http://cgi.ebay.com/HTC-6175-Touch-P...item20b0fdd45e