Cam,
I wouldn't put poly-planars on my boat, because no, I don't like the sound. That being said, have you ever spent any time with the guys in the big fishing boats? They have their systems blaring at just-below-painful levels, and I'll give the devil (poly-planar) their due. They hold up to that kind of abuse. Are they what I'd listen to at home? Nope.
The other thing is they stand up to getting wet. As in turn the hose on them while you're washing the boat soaking wet. Not many speakers will put up with that for very long.
(I knew someone would shoot me for saying poly-planar. Now someone can shoot at me for saying Clarion, and get it over with.
)
Once more: No I wouldn't personally buy either one for use at home, but they can be played loud, they don't care if they get wet, and they're better than some of the even worse junk that's out there! (Like Pyle, Pyramid, Bose) If you want a real sound system, put it in the cabin. If you want to rock out while you're doing a power reach in 20 kts, Clarion, Poly-Planar, Pioneer and some of the others will do fine.