jury is still out on longevity obviously, but I think the plastic hulls are going to outpace the fiberglass hulls as far as maintenance...they can just sit in the water and they don't get stained or fade out like gel coat...plus their black so as long as you have some kind of uv protectant on the parts getting hit by sun, they are going to look the exact same in 20 years...
You feel everything with the plastic vs the fiberglass which seem to cut through the water much better...the plastic rides over top everything...50mph on my yamaha vx is smoothhh...50mph on the spark feels like 100mph with just simple wakes created by other watercraft on a lake...
If your looking for smooth ride at higher speeds, do not get a spark lol...if your looking for a cheap, economical ski that is great on gas and will launch off of every wake, is easy to do tailspins and toss around, and most likely will be easy to maintain, then you'll be satisfied with a spark...
With that said, I keep mine on a lake...and I love them for cruising around and playing around...but my neighbors 05' Yami GP1300R will blow the doors off my spark (if it had doors) on the water...and will cut through the water at 70mph more comfortably then my spark will at 30mph...but its also a 2 stroke ski that will prob require more maintenance over time then my sparks will...