No my impressions is solely for customs. But I have also heard K10 and roxanne universals. They actually both sound a little different from the custom versions (depending what tips you use). But not by much.
I think the universal (demo) K10 has less bass rumble, making it a little more neutral than my custom.
Very good, I get it now. How about build quality on your customs (roxanne and K10), any differences worth mentioning ?