I've never used it, but I've heard great things about it. The UA unit seems to be a little better quality, from reviews and shootouts. I personally would go for the Universal Audio one myself. The thing I like more about the PowerCore though, is that it's available in the compact little external case with a FireWire connection. If I were to get one, which I might in a few weeks for my laptop, I would have to go for the TC compact, since I can't use the PCI card versions (der), and I don't really need it for my G5 as I have plenty of processing power to handle the plugs I typically use on sessions already. I wish UA would make their UAD-1 into something like that. Oh well. I think it's pretty much a toss-up man, they both get great reviews and are neck-and-neck in shootouts.
~006