I've been retesting the Imp. exc. at least, and it's looking like I get around 33 eff/pec @ 240% MU.
The break rate should be lower on an adj. given the new enhancer mechanics, so if I plug in my current (still rough) break rate on an imp., the adj. eff should be at least ~27 eff/pec given the same cost of a tier 1 enhancer.