But to your point, it's very risky and NOT something most people should even consider. There's no way in hell I'd sell my soul to a credit card company at 20% APR either.
I have never bootstrapped a company on a CC. Fortunately this latest endeavor is all about micro-transactions so we're cash-flow positive very quickly. If I bootstrapped on a CC, I would never exceed a debt level more than the value of personal assets (car, equipment, etc..). Always plan an exit...
I've heard of them closing accounts before, in the book "Mavericks at Work" ING actually promotes the behavior of rejecting bad customers. While I agree, I think there needs to be absolute transparency around their banning policy so it's crystal clear form the start to prevent issues like yours.
I currently use an AMEX Blue (cash back) for my personal stuff, balance is paid IN FULL every month. And we have a business checking account for the iPhone company. $5/month through Wells Fargo.
While I keep a few accounts at Wells Fargo, I bank through ING Direct. Love everything about ING, and they have great leadership. One complaint: for an online bank their web interface is freaking terrible.