RE: evo80 or combat87?
I have both these boards and both are very nice and overlap a bit in what they can do. The Kombat is easier to get to plane, especially in onhore waves, with big sails (5.5 and up) and when you're underpowered. To "get even" on the E80 you have to do more work yourself, so to say.
On a wave, the Kombat is surprisingly good and especially in cross on-sideshore and nice but not super fast or really big wave the Kombat shines. It feel fairly close to a Pure Acid in these conditions. When it get bigger and faster you will pay a littly for the extra tail width (compared to Acids) and the combination of high speed and relative width requires more power and technique from the rider. At the oterh hand, almost onshore and slow waves, it looses out compared to and EVO because you're almost enivitably gonna loose speed when pushing the straighter rockerd Kombat through a tight bottom turn (when there is not much sail or wave drive). Regardless of wave, the K87 prefers a more drawn out turn than the EVO.
The EVO 80 is a true wonder for versatility on a wave and it rocks from super small and super slow well into the big and fast range. The part of a wave ride where most people have problems is the transition from a bottom turn into getting more vertical and hit the lip. This the EVO does practically on autopilot and that is the reason many peeple feel they develope into better wave sailors on that board. But as I wrote above, you pay a bit in straightline feel.
Note that alla this is in a direct comparasion. If you only sail the EVO, you might think its just terrific in a straightline and if you only sail the Kombat You might love its behaviour also on smaller or bigger waves (not just the medium ones).
One way to differ between them is to say that if you live for riding waves frontside, than the EVO is probably it while if you more do blasting and jumping and only push the frontside riding when you get a good setup, than the K87 might be a better choice.
Please ask again of you want more specific info.