Well my patience ran out and I flashed the .AD3 BIOS today. After several hours of tinkering I think MSI is on the right track, but there are a few issues.
In my system, setting PBO is any position except "disabled" led to really high temps during testing; e.g. running Cinebench 23 multi-core, the CPU immediately shot up to 84C and peaked at 88. "Safe" perhaps, but I am not at all comfortable with that. And that was AFTER setting my Curve Optimization to nearly -30 on each core. The "Advanced" option for the PPT, TDC and EDC "PBO Limits" that should have allowed me to moderate the thermals is "manual" -- so I could lower the stock PPT and/or EDC -- but there is no "manual" in the menu here; only auto, "motherboard" and "disabled." My understanding is that either of the latter options will effectively RAISE the stock limits... not something I want with the CPU already throttling in the high 80s. FWIW the 1.2.0.6(c) BIOS DID have the ability to lower (but not raise) PPT, TDC and EDC individually.
Another possible option to lower the Package Power Limit -- under the CBS menu -- has zero apparent effect unless PBO is disabled.
Finally, the option to set max boost (above 4450/4550) IS THERE, but when I tried any setting (even 25 Mhz which is the lowest possible), the result was that the CPU did not boost AT ALL... stayed at 35-3600 Mhz at all times regardless of load. That's definitely a bug of some kind.
Bottom line is I'm still tweaking the settings to try and equal the performance I had with MSI's AGESA 1.2.0.6(c) BIOS plus PBO2 Tuner. Will continue testing tomorrow.