When I saw those Cheetahs... I started salivating! Big power in a Speedlite form factor.
I have read nothing but glowing reviews on those units. Especially from wedding photographers. I'm going to wait a while and see if Phottix will come out with something similar. I don't want to use multiple radio systems and I love my Phottix gear. Putting a bare-bulb into a softbox always looks better than a speedlite.
Have you tried using different batteries in your lights? Say NiHM vs Lithium. How about taking them in for service?
Good work and website BTW