Commando,
I say go for it. I was essentially in the same boat as you. Really wanted a semi auto MP5/10. But wasn't willing to pay $6000 for one.
I put myself on the waiting list for a Cohaire/Special Weapons/Vector clone and am now the proud owner of one. Have I had problems? Gun never ejected properly. Bolt hold open device broke. Gun shot about 6" to the left at 7.5 yards. Gun is currently at Cohaire for a repair. Vector has covered all shipping.
Will it come back fully functional? Well they've supposedly got it running 100% and have it bore sighted. If the gun comes back 100% I'm a happy camper and it will definitely be worth the minor aggravation I've been through.
If the gun still has problems, it's off to Jayson who hopefully will be able to get it to function. Even if he charges me a couple of hundred bucks - it's still a lot cheaper than any other alternative I have available to me.
If you want a 10mm version, I'd act fast though. Cohaire has stopped mfg. these. I don't think Vector is going to pick up where Cohaire left off. I think a total of 40-50 were made in the 10mm version and that includes at least three different configurations. I think even fewer made in .357.
If you don't mind the .40 S&W version, that would probably be the way to go. This seems to be the least problematic and most reliable of the 3 versions Cohaire is making.