The only downside to studs .vs bolts is cost to buy them. You already have them so that's a moot point.
Cometics are great....... IF you have a SMOOTH, FLAT surface that's setup for Cometics. They seal well enough to crack pistons if you detonate hard enough. If you just slap a set on an unmachined deck with an unmachined head (or ones with the wrong kind of surface texture) then, yes, "Cometics are crap".
If you have flat smooth surfaces to work with, hit both of them with a diamond stone and make them even smoother, countersink the hell out of the head stud holes, remove the rivet on the ex side of the gaskets and coat all the inner and outer surfaces with copper coat (yes, I know... Cometic says not to...) and bolt them down. For added insurance torque cycle the studs a few times so the threads can get good and married. Then see if you can shoot the crank out of the oil pan!