There are several advantages to running adjustables;
0) Possibly/probably better geometry.
1) setting lifter preload.
1.2) resetting preload cuz you didn't set it right the first time.
1.4) resetting the preload periodically for wear compensation
1.6) compensating for varying pushrod heights due to decks not parallel to the crank or heads not machined flat.
1.8) changing the lifter preload cuz .080 to .095 is a ridiculously huge amount of preload;( I run 1/2 turn). Why do you say that? Factory was all the way to like .120
Not saying your wrong, just remember trying to figure this out myself. I did a cam in my magnum, used harland sharp roller rockers. Non adjustable. Stock pushrods and they had like .090 preload. Hughes said it was fine, but seemed high to me.
3) roller tips and bushed bores
5) ability to reset the Quench with thinner or thicker head gaskets
7) strength, and freedom from push-rod punch-thru.
8) they look really hi-performance.
9) bragging rights
