Yesterday I finally busted a cap in ASMM's proverbial ass, setting sga_target back to 0 and manually configuring the various SGA member pool sizes. After my first problems with ASMM, I began reading more and more about "immaturities" with ASMM which I hadn't come across before, particularly with rapid-fire SGA fluctuations thrashing the hell out of things. Perhaps that's what I get when I only read Oracle-published white papers on new and OMGAWESOME Oracle technologies.
So, not wanting a replay of the 2:30 AM ORA-00600 page, I decided to just go back to good old static SGA allocation.
I also doubled my pga_aggregate_target to 1G, based on the advisor table advice. Hopefully overallocations will be a thing of the past! After a whopping 4 hours of normal usage, my cache hit percentage is up from 85% to 97%. Dare to dream!