J.P.
F.,
Funny I was just researching this myself :). We have the 595 which has worked flawlessly for the last two years. Taken quite a few bumps and bruises along the way as well. It's the "pet" one that is supposed to be better at taking care of pet hair etc.
I would definitely take a look at the irobot website as they just released a new "900" series which looks substantially better in terms of technology (price too I'm sure ;(.
What's funny is I don't think there is really any competition...basically it's irobot or nothing.
Good luck! These things are addictive.
- Jake
UPDATE - oh no! I see you were asking about the mop! Looks like I need to get a cup of coffee or three to read things a bit better. Well I'll leave my above comment as is, we love the vacuum, but have never used the mop.