In my experience clean/light CV's are by far the best for almost every job - particularly engineering jobs. The exception being designers.
What sort of CV's are you seeing come in?
I know quite a few HR types who will find a snazzy looking CV and instantly demote it, on the basis that the sizzle is probably hiding some inadequacy (this is not necessarily a bad marker in my experience).
It would be interesting to see if the investment in this pays off for the candidate - whether the really high quality of the design flips it over that danger marker.