It's easy to say that exchanges are just for exchanging and people should cash in and out quickly.  The reality is that there are costs in terms of fees and inconvenience (captchas, email verifies, delays) that make it difficult to do so.  So many people end up just leaving money on the exchanges.  And get bitten when they fail.   Is Ripple any different in this regard?   Is it 0 cost in terms of fees and near zero in terms of inconvenience to cash out my bitcoin IOU for a real bitcoin?

Otherwise, I don't see how that is much different from any of the other exchanges.... entities that I put approx zero trust in.