I personally HATE the dang numbers with all the UA express. I work in a ramp tower at ORD and it is so annoying having to repeat similar sounding callsigns. I can't imagine what it's like for center, tracon, or tower controllers having to deal with it. on the ramp, it's not so dangerous, but airborne during rush hours it's got to be nasty. Everyday there are 2 flights I know of that come in the exact time here at ORD, Skywest 5808 and 6808. The company operations almost always assigns them the same gate as one another so that makes it even MORE frustrating. But it's still fun.