I think I see more clearly the trouble on this subject. When Mt. Gox started, it was only BTC-LRUSD, so it was always the case that counter-parties had the currency desired in the trades that executed.

But now, Mt. Gox has bent their exchange into trading between BTC and USD-like-thingys. So one side of trading is funding their account with BTC. The other side of trading is funding their account by one of a number of different means, all said to represent USD. Bank wires (most like USD), LRUSD, Dwolla, etc. But, once all this stuff settles in the trader's account, it's all just treated simply as generic USD-like-thingys.

So if Alice, Bob, and Gwen are the only Mt. Gox users; Alice deposits 50 LRUSD, Bob deposits $50 via bank wire, and Gwen exchanges with these two for her 6.25 BTC. Now Gwen has $100 in her account, but it's really $50 and $50 LRUSD. If she then goes to withdraw her entire balance via LR, Mt. Gox has to horse about behind the scenes and buy some LR with formerly Bob's $50 bank wire deposit, to give to Gwen.

And it is THIS which is creating the delay. Too many people came into the system with USD-like-thingys other than LR, to find matches with the people trying to now withdraw their USD-like-thingy balances to LR accounts.

I hope Mt. Gox isn't upset about that. They dug that hole themselves all right. They effectively chose to become a sort of exchanger by aggregating all the various USD-like-thingys they accept into a single tradeable entity. At that point they were working an averages scheme to avoid having to convert among the thingy types. Then, they got hit with demands in excess of their expectations.

Do I have that right?