i test drove the genesis 3.8 track as well as their 3.8 auto, but when I drove the Z it was "love at first sight" so to speak. totally different animal. the Z feels special. the genesis is a really nice and loaded car though. great interior and great price.
if you're driving auto, the Z will be an even more massive improvement. if manual, i'd stay away from 09's due to oil consumption issues. so far the car has been really reliable even though i got it with high mileage so no worries there.
i always like to let you genesis guys hear my exhaust as i'm passing lol
i'd say go drive a Z and see how much more enjoyment you'll get. oh and drive one with a sport package.