So, concerning your competent pilot, I can envisage a situation where a pilot routinely flies in IMC, relying on the autopilot and then has an autopilot failure in cloud. If he has not routinely practiced manual flying on instruments, I can see him easily losing control. Admittedly, it would be more likely a spiral dive than a spin, but the result would be the same, unless he came out of cloud or had the red handle in a Cirrus.
I think the problem I have with this is "if he can not routinely fly in IMC with an auto pilot failure then that is the problem" and renders the pilot incompetent, his ability to recover from a spin is not even going to come into the equation as I would suggest very unlikely he will not recover.
I stand by my SOP and if I am in a spin for whatever reason (my lack of training, incompetency, mechanical or avionics failure) I will be pulling the chute.
I do not know the facts but I am not aware of any Cirrus Pilots that claim to inadvertently got into a spin and recovered, I know of a few that did not recover and I know about a few who pulled the chute and survived.