I'm searching someone who use them or tryed them almost once. What do you think of them? Are they worth their point cost? For what purpose are they better? How many do you play of them?

I think in normal game, with just a single monster/light vehicle slot, generally Meka is more useful. Dragonraiders are fast, but still slowed by terrain (why?) they probably won't do a thing in the first turn, and they are not so powerful, not almighty, but more oriented to kill masses of weak troops (and stun them) with their good flame template.
Maybe with the Rat ki power they could survive enough to bring them close and then be useful. Maybe two of them are just too few, but 4 are 400 point, almost half the total amount of normal 1000 game I usually play... Maybe 3 is better.

what do you think?

I have never faced them but every Mishima battle report I have read says they are just not worth the points.

Kunshu are CC unitt, with flamer and 12" SMG. Their main drawback is their cost/durability. They do have only W3 and by the time they attack they are mostly wounded and die right away after attacking. They need a small durability buff and they will be alternative for Meka.