I'm a total convert!
I consider myself becoming an intermediate paddler, weigh about 73kg, am 173 tall (and have proportionally short legs for that). So I need a stable boat, with short leg length, and it must be built for a light person (compared to your std 6'+ 90kg paddler).
My options are limited to Horizon or XT. Dorado is too unstable for my weight. Swordfish leg length is too long. Guevarra leg length too long. Synergy2 is just a little bit too unstable for me in rough seas (I think I'm underweight for it too). ... or the CLK...
Genius was started by a guy with roughly my height/weight cos he couldn't find boats for his size... (that's on another thread somewhere on this forum).
OK, so nuf about me - but at least you know where this is coming from. I'll compare CLK to Horizon & XT below.
The boat IS stable. I think maybe slightly less so than the Horizon/XT options, but not noticeably so. I've had it in pretty rough conditions and haven't come out due to conditions. (Langebaan Discovery course a few weeks back)
The boat is faster than the other 2. But I paddled the Swordfish on Saturday - Swordfish is faster. It is also tippier (and too long for me in the legs). If you can paddle the Swordfish, it's probably a better bet. If I was 15cm taller in the legs, I'd be tempted.
CLK catches much smaller runs than the others. This surprised me as a newish paddler, cos I'd never been able to get onto small waves. This makes it a really fun boat. Comparing the boats upside down next to each other (CLK vs Horizon), you can see the CLK is rounder than Horizon, looks faster, and is a bit (20cm?) longer.
Then there's the weight for price difference. When I bought the CLK it was CHEAP - the epoxy vacuum boat same price as the normal glass Horizon. With a weight difference of +-4kgs (not weighed the CLK, but I was told it was 14kg in vacuum - I'll have to check soon). Compared to the 18kg Horizon, that makes a HUGE difference.
For the ladies, the weight helps even more, now they can also carry the ski easily, put it onto car more easily etc. A female friend got it for that reason, and as more a beginner than me, loves it.
Other than that,
our instructors seem to love the boat it has been alleged that there are some people in Cape Town who conduct surfski lessons, who claim to prefer to use the CLK rather than the Horizon (cos its just so much fun) - so even a (mythical) more advanced paddler might possibly see the boat as fun to ride.
Did I say I was some evangelical convert?
(no, I don't work for them B-) - I'm just a part-time paddling desk-jockey)