I prefer raised seats. With my Pyranha I only raise my seat about an inch with regular foam, in addition to the standard outfitting.
When I was younger and smaller and trying to flatwater cartwheel a Riot Glide, I eventually raised my seat a full 7" from the bottom of the boat. I don't recommend this since it made the boat very tippy, and tricky to roll. It also was sweet because it gave me the leverage to really move the boat and throw the boat around despite my small size and long boat.
There is a happy medium. If you feel short, raise it up a bit. I've found that 1/2" increments are noticeable.