Mine is actually a 7'6", not a 7'0".
And I haven't ever ridden one of the really short comets. But I love my Comet, and have ridden it in everything from knee-high mush to DOH point waves. The DOH was too much for the board, but it's performed well up to a couple of feet overhead. I ride it more like a longboard than a standard shortboard. It's sweet.
Anyway, the major differences that I see between the 6' comet and any other more modern 6' single fin shortboard are:
1)Weight - The Comet will probably come in at between 12 and 16 lbs. my 7'6" weighs about 20. Most modern single fins (even with gloss coat and heavier glassing) are gonna be well under 10lbs.
2)Rails - The Comet has very knifey, thinned out rails with a pretty hard edge. Most of the modern single fins I've seen have pretty forgiving, eggish type rails - like a typical thruster.
3)Fin - You buy a Comet, and you get a glassed-on, heavy 10.5" fin. No moving it around or changing fins for different conditions. It's where Gene thinks it's best, and that's it.
The Comet is just an all together different beast than most of the single fins I've seen around. That's not a good or bad thing, it's just different. All of the above factors make it, in my experience, "easier" to ride a modern single fin. Again, that's not always good. The way that the Comet is built makes your technique, foot placement, weight distribution, and trimming really essential to being able to ride it successfully. You HAVE to think when you ride it. It'll probably make you a better surfer in the long run. Sometimes I space and try to ride it like a thruster - it don't work that way and I wind up on my ass.
If I had the cash right now, I'd go out today and order BOTH a 6'0" Comet AND a 6'0" CI single fin. They are way different boards, and I'd learn a lot from surfing both of them. If you can only buy one, you should educate yourself as much as possible about the differences - they are more different than they are alike.
If you're looking for something that'll be more like riding a standard thruster, buy a regular single fin shortboard. If you're looking for a challenge, and an experience, buy the Comet.
One other thing. The Cooperfishes are definitely among the most well-crafted and well-built surfboards in the world. They are impeccably made. Anyone who appreciates surfboards knows the level of craft put into making one. They are well worth what they cost.