I have the one from Verizon also (got it on Ebay) and works awesome. It has inserts that fit phone, phone with gel case, and phone with extended batter but no case (my case is gel, easy to remove and put on, so no issue for me).
I am using the Otterbox Defender with Extended battery on my Rezound. There are other threads on this, so look at those for illustrations.....might even be a YouTube video. Basically, you leave the hard plastic back cover off, just using the silicone and the front cover. Not small, but not much bigger than the holster shell combo Verizon sells. The only thing I do not like is the otterbox screen protector that is pre-installed. I will remove this if I decide to keep the case. This is day 2 trying it out.