Keep in mind that the Interlagos/Bulldozer 82xx 16c chips have two 8 core integer processors, but they share a single FPU and fetch/decode/execute units so they aren't really full blown 16c chips. Clock for clock they aren't as efficient as Magny Cours/Istanbul 61xx chips. They also tend to be a bit more power hungry than MC's. Sometimes IL deals pop up, but IL chips really aren't worth any premium over MC's for folding.
The Abu Dhabi/Piledriver 63xx series of chips is sort of an optimized Interlagos. Some bottlenecks were opened up, but the L1 cache deficiency is still the same as Interlagos. Clockspeed capability was improved and 1866 DDR is supported on boards with that capability. Power suckage per op is substantially better, 20% or so, than Interlagos. There are some folders getting good performance from 63xxx chips, but they are still very pricey. 2.8/3.2 ghz 6386 AD chips are selling for $850 and up and 2.5/2.8 6380's can be had for $700 or so. The low end 6366HE chips are still going for $500 and up. No budget folding with these babies for a while.
I don't think tear's hacked bios supports any overclocking with IL/AD chips.
IMO, unless you get an exceptionally good deal on IL or AD chips, MC is still the way to go for G34 4p's.