My experience (and family's experience) with nissan/infiniti products is this:
Originally Posted by TheOtherDave
Nissan's quality control was less than stellar.
The lexus is pretty old, which may be a factor in a luxury segment, but I don't doubt that it would cost you less money (possibly way less) over the long haul. I've never driven one, so I can't comment on "sportyness." I have driven the G35 right before they switched over to the 3.7, and it was pretty OK (flappy paddle transmission), but I still didn't feel it was properly "sporty"
h: The gs400 is probably a pontoon boat in comparison, but I don't really know.