I have a pack or 2 of the new Nano batteries now. I needed a small pack for my Multiplex Fox conversion and I had to replace a puffed lipo pack. I am really happy with those new batteries. Faster charging at the field and they seem to hold their power really well.
See here for more information:
http://hobbyking.com/hobbyking/store...8&ParentCat=85
The 2200 mAh pack I have can be charged at 8C, which is 8 times faster than my previous battery.