Roomba

I would really like a Roomba, and I'm trying to figure out which one to get. Are all of the extra features worth it, like the voice demonstration and self charging base.

I'm trying to decide between the 532 (pet model), 510 or one of the 400 series.
Can someone please help me
Which model do you have?
Do you love it?
Do you wish you got a higher model?

Thanks