Icarus, I highly recommend searching for reviews here on TalkBass. Although the old Russian (black) and Sovtek (green) Big Muffs have held favor with bassists for years, the Bass Big Muff is an even better improvement. EHX actually based the Bass Big Muff on its Russian predecessors because of how bassists favor them.
There are lots of Bass Big Muff reviews on TalkBass. I even wrote one myself (although I was also comparing it against a very different fuzz pedal).
With the Bass Big Muff, there's little reason to use the old ones anymore. The Bass Big Muff does sound a bit different, but it's still very similar to the old discontinued Sovtek version (which is why it's green, just like the old one

. The features, size, and sound make it a clear winner.
Without question, go for the Bass Big Muff.
Oh, and for the record, the USSR ceased to exist nearly two decades ago.
On second thought, a lot of ex-KGB guys are still running the place...
