I considered Arax and found lots of people who were happy with them, but when I found I could get a bargain condition Mamiya RB67-ProS from KEH for under $400 I decided to go with something I knew would stand up to actual use.
The biggest problem with Arax is that they're starting with products from the Arsenal factory, so even if they "get it right" before they ship it to you, there's a chance something will break and you'll end up sending it back. Postage for me from the US to Arax would have quickly added up to more than the system cost. The RB67, on the other hand, is likely to work for longer than I live.
Since the pro's have dumped MF equipment onto the market at such a high rate over the last few years, there's little reason to consider entering the crap-shoot involved in ex-Soviet products. The prices just aren't justified when you can get high quality equipment for a song.