I run the CE on a high bite indoor track and have had great success. I run the gear diff and shocks on the front of the rear arms, but it's really down to what you prefer. There's guys on here that run on a mid to high traction track and much prefer the DE and a ball diff, meanwhile I much prefer my CE with a gear diff, there's no correct answer other than trying stuff for yourself. The one thing I noticed about the XB4 which has carried over to the XB2 is just how easy it is to work on and tune compared to other cars. If you want to try the ball diff and gear diff, you can change it out in a couple minutes and be back on the track testing.
Here's my setup, I might not go directly to it but maybe you can find some ideas to try. The car is pretty good with the stock setup, just has a lot of roll and droop in the front which is easily fixable. I wouldn't try to overcomplicate dialing in the setup before ever running the car, I think the stock setup might surprise you.
http://forum.teamxray.com/xform/inde...setup=xb2_2016