If I was to use MySQL I would probably use InnoDB instead of MyISAM at least. Even if you have UPS and backup power to keep everything running at all times, it's pretty neat to be able to ROLLBACK when you've forgot that "AND id=12345" in your DELETE FROM and saw "654321 rows affected"
Very well, when it comes to the stability of MySQL I have managed to get crashed MyISAM tables when testing some alpha version a few years ago. (It took 48+ hours to do an REPAIR TABLE ... EXTENDED, and the table crashed again soon.)
However, I have never managed to break something with a stable version or with 5.0.0-alpha.
Don't forget the backups, of course...