I'm probably one of the unlucky ones, but as far as I'm concerned the 650 primer system sucks. I end up with more flipped primers and jammed primers that don't drop out and keep going around to gum up the works. Small primers in particular, CCI especially.
I've chamfered the primer disk holes, run it dry, run it lubricated, etc., etc. I have multiple full primer setups. My SDB never fails me but the XL650 sometimes is a PITA. I'm not getting rid of it, as I generally love the machine but in my case the primer system is the Achille's heel. I'd welcome an XL750 "just in case" it would be better.
If Dillon sends me a core I'll update and report back ...