I haven't done it, but now maybe I will.
That actually sounds like it went pretty smooth. You're moving an assload of data, so 18 hours is actually pretty fast. I think it took me over two weeks to get all my stuff moved in lala's people mover back in the day, although I don't think I left it running straight overnight.
I'd also say only losing two albums is pretty good. When you rip stuff, who knows what gets put into the ID3 tag? Like usually they'll pull it off of Gracenote or something, but what if Gracenote has an error, and then later they fixed it so what you have is not what Apple has. Or somewhere along the line you accidentally changed a tag, or some data glitch scrambled something. I mean, the vast majority of the time it works, but there's always a big of leakage.