"MySQL has simply bitten the tail off my data and happily stored the rest without any errors or warnings. OK, I should have RTFM but still, the idea of a database corrupting my data without any warning makes me very uncomfortable..."

That is just insane. I heard about it a couple months ago and wondered what were those folks smoking when they wrote it like that.

The hot backups thing never crossed my mind, but is very interesting. Of course, it relies on transaction consistency and MySQL has the option (shivers) of not having it, thus the locking demands.

From what I know (I am a PostgreSQL guy too), when you use a transaction-aware data store in MySQL, these behaviours are gone (along with any performance edge it may have over PostgreSQL, but that's another story), so, you may want to give it a try.