I agree. You can't set up the nut slots low enough to "play like butter" if the frets are uneven. You can make a cheap bass play just as easily as a high end bass if you're willing to work on it.
That doesn't means it's just as good as a high end bass. It just means it's easy to play without getting a lot of fret buzz.
Ed
Yep, I agree too. there are lots of things that make a difference but the nut slots and frets are mega-important plus how straight or how bowed you want the neck.