I've used Digipawn before and have been quite happy with them. Response time has normally been literally minutes. The paperwork involved is minimal and everything can be completed in 24 hours.
I can't speak for Rick, but based on what I've seen, I think that he is valuing domains at what he could sell them for quickly at a reseller level. That's pretty fair, as if you default on the loan, that is how he has to get his money back.
Borrowing on a credit card is probably better than using Domain Capital or Digipawn. But the purpose of each is quite different. Digipawn is great if you need funds quickly to close a deal and expect to pay the funds back soon.
Also, if you're self-employed, and earn your income from the internet, it can be hard to get credit from traditional sources, as quite frankly they don't understand what it is you do, no matter how simply you break it down for them. And they'll never consider the value of your domains as collateral - so you could have a very valuable domain portfolio, and still not be able to get traditional financing.