Because of buck overheads and other things, the low-end hashing efficiency of the 2-chip BM1384 would only be at best a marginal improvement over the existing Compac. However, overclocking is where it'll really shine. The old stick's 5W performance was around 12GH, where 15GH is hopefully a conservative estimate for this one; 7W should see over 20GH instead of 16GH and the top-end 10W would get you about 27GH instead of the old stick's maybe hitting 20GH if it didn't burst into flames. Cooling should also be better because of the reduced heat density of two chips.
Looking foreword to this to push it to the max, hope it don't let out the magic smoke. I will at least get 2, one for normal mining and one for "testing". The one chip compac didn't seem to get too hot anywhere as far as I pushed it. Only had the IR temp gun but I think it did very well considering I topped it out at around 25+Gh.