I can't speak for anyone else, but my experience with USC has been nothing but positive. I bought my first cutter from USC via eBay. I would have not hesitated to buy my second cutter from them, had I not been able to find a local company near me that could give me a huge price break on the shipping.
I've only needed to speak with their support team once or twice, and both times they were very responsive, and even accommodated the fact that I'm basically in a time zone all on my own, and made a point to schedule a call back with me.
Luckily for me, my cutter has been virtually flawless and has performed well for me for close to 12 years.
Buy the best cutter that you budget will allow and I think you will be a happy camper - with the machine, with support, and the unofficial support of the forum.