yeah, I wouldn't get the cGEM if you have enough money to get something with a less than 5 arcsec tracking error.
I'm also playing with the edge HD 11 inch. It's not easy like other SCT's, not if you want the stars round across the field of view. There's a tiny quarter inch window of motion that the focuser can travel else the stars look like donuts. So I'm trying to figure out how to find an autofocuser that can do the job.
Not sure what upgrades are on the DX, but the original cGEM, one thing that's not trivial is how much the wires get tangled as the scope slews. The other is simply that the tracking performance isn't great for the money. You can make it a lot better with Pempro Pec tools but I dunno, I'd rather not buy a high priced low end mount and would much rather get a low priced medium range mount like the CGE pro. That's all i'm saying. CGE pro will make your life easier, make it more enjoyable to telescope. I know OPT has an open box one for $4200..
See my review of the CGEM in the "Equipment Review" group. CGEM DX uses the exact same motors and very likely the same firmware. CGE Pro also probably has the same firmware issue, but I don't know anything about the motors, beyond that they are servos.
Nevertheless, it is Celestron's service department that is the main reason I wouldn't recommend their products.