I've got a 10'6 fanatic fly sup and am 95kg. I wouldn't say sup's plane in the same manner as a shortboard. Even with a 4.5 on in 10-12 knots the fly takes off even if you just hook onto a big bit of chop. Sups are very efficient hulls but not so much of a planing hull so kinda pointless in using a big sail.
My only reservation for sups as a lightwind waveboard is their construction. If you want a light, easy to handle, good looking board think of them as similarly built as a surfboard so it will be dinged by mast/boom though eva use helps this a bit. You could always go to the heavier constructions though but the light weight is nice when putting them on the roof etc.
If you want something that planes more traditionally and is built to take the extra pressures as a sailboard in surf & can jump then get a kona. If you want something to happily paddle round on in the flat, good fun in sub-planing winds and can take into the surf to ride the waves then get the sup.
Sups are different but they are very versatile and heaps of fun
