No issues. I've had an American Express Clear credit card for a number of years with them and they never lock me out of my account for mysterious unexplained reasons. The credit limit increase process is pretty easy, though it would be nice if they gave you some idea of what kind of range to ask for (I looked up third party suggestions via search). It was a bit weird that they didn't auto-increase my credit limit over time like my other credit cards, but some might see that as a benefit.
