I always use a faceplate with facegrain hollowing and will only use a chuck on a tall end-grain hollowing when supported by a steady-rest. And over 15" dia, a 6" faceplate.
My concern on facegrain is the sheer line where the tenon connects to the piece - when it sheers, it sheers quick. But the sheer factor aside, I don't think there are many out there that can hollow a piece of any size without an occasional "snag".
My bases are always 4" or a bit less. On a Oneway 6", use 1.25" #14 on the six inside holes and 1" with ground tips on the outside - drill holes with a depth stop. I mount logs up to 300-lbs and have never had a problem or used longer screws. You can "dive under" the faceplate and create a 4" base with no problem after the weight is down and the rigors of hollowing are done.
A properly mounted faceplate takes a bit of time - certainly more than a chuck. But, then again, we're "re-creating" ourselves. And a chunk of wood coming off at any speed can quickly "un-create"...literally.