Not to be argumentative but it's SOP to put a 250 hour pilot next to a 10,000 hour captain in the airlines....so anything the airline guys say with regard to this subject is suspect. It's also patently ridiculous to consider a 121 ops where the pilots fly the same routes for three months straight, never having to plan a trip or file flight plans, or buy fuel, as being anything akin to a 91 captain getting the call the night before and boss wants an international trip in the morning.
This scenario breaks down fast for the airline guy who can't plan, can't manage, can't work on his own, now saddled with the boss's idiot nephew who can't fly, but none the less is there, deal with it...now your airline guy is a single pilot captain in a X. He wanted the paycheck, he's going to have to live with it.
As far as the X being a hand full, sure, I get the speed issues, but anyone that I have talked to flying the X, has said the same thing...they never go .92, burns too much fuel, so it's .85, just like the Astra, or Falcon, or Lear...so the speeds are nothing out of the ordinary...so what if it's slippery on the decent, pull the power back, if your totally past it, throw out the brakes.
Personally my issue as a captain in this equation has zip to do with the plane, but who I have to sit next to and how they are going to contribute to the operation.