Clay, I can only speak for myself, never discussed racing technics with my fellow friends/competitors
.
One of those (Laverda Twin 860) had a aluminium rear disc (just alu, no sprayed Zanzani) because He didn't use it anyway but TechControl demanded it.
I don't recall even touching mine (except when standing still on a ramp), the front was good enough to flip the bike (and did it twice) so I saw no use for the rear brake. Sliding into corners dirttrack-style wasn't discovered (yet) or at least not done in BoTT in the 80's.
Sliding the bike going out was fun, sliding the bike going down was costly.
I guess You'll just have to fit one on Your favorite bike and try it.
The braking, not the sliding down
ciao
ducadini