Wow! Thanks for that post; I’ve been looking on eBay for a US Big Muff. I didn’t realise it had been reissued.
I’ve got the same black/yellow version as you. I love it, although I haven’t had a chance to compare it to a real US one. I think the Russion one sounds good, but I’ve had problems with the footswitch being a bit unreliable (sometimes the effect switches on, but the output volumes goes really low).
I’m going to order one (assuming they’re available in the UK). I’ll post a comparison when I get it.