Would it be safe to use this if you're transferring a very large amount of money, for example to buy a house in a foreign country? Anyone have experiences (good or bad) with large transfers they'd like to share?
They are not covered by any kind of FDIC equivalent (and in fairness there's not really any good deposit insurance regime for international accounts). They claim to use ringfenced accounts for customer funds but AIUI that's all self-certified (and wasn't there at all when they first started, although I understand they've gotten a bit more professional in various ways). I wouldn't worry too much about making a one-off transfer under normal circumstances - the risk of them going bankrupt in the next week is pretty low - but I'd be a little wary of keeping a substantial balance with them over the long term.