My keyed chuck slips when torque gets a bit high. Seems like it is the weak link in the system and maybe protects the JT and MT tapers from spinning.
If I was using a quality keyless chuck that does not slip, in a tailstock, extra attention would be given to choosing and feeding the drill so that it does not pull or slip on the taper(s).
I would probably want to use a MT-JT arbor instead of an integral shank just to keep my options open for other uses of the chuck in the future.