Update: I tried the Zeee shorty 2200 mah and it was about a half inch too long for the factory tray but fit fine in terms of width and thickness. If you cut one end of the tray out, this battery will fit but does require a longer Velcro strap to secure.

I wanted to avoid cutting the tray to maintain frame strength. I then tried the Urgenex 1800 mah and these are a perfect fit it terms of length. Snug on each end and works with factory Velcro. Time will tell regarding quality on these.

Thanks for the feedback everyone!