I bought mine for $2400 before the price drop to $2k before December, but then I had it for Thanksgiving and Christmas and that was a lot of indoor high ISO stuff.
Hard to regret though, I'm not sure I would/could have gone up to what would have been $4k with all the extras.
But then for me (buying a MkII for $2400, just an extra $1k for good AF and possibly a bit extra ISO?
Dunno, 50/50. I might upgrade again this time next year after seeing what the reviews are like from people using it. I might manage to talk myself out of it though, it would cost $2k to change and that's a lot of nice glass.