I rode the SPK Kaos this year. I found that after a while, only having 2 buckles was not the best setup support-wise, and you either have to rachet your foot in super tight, which hurts, or have it looser which increases shin bang.
Because of the way they're designed, they're also difficult to get on. In the first few weeks I had them, I had to keep my foot in the liner, then put the liner in, or take it out of the shell to put them on or take them off.
Also, the built quality is poor. The power strap fell off after 2 weeks on one boot, the plastic keeps getting caught, and pinches the foot when closing every so often, and you have to manual wrench the boot open to put it back in place.
On the plus side:
They are significantly wider than Full Tilt, so for someone with a wider foot, these should be an option.
Also, the fur liner is very warm
Cheaper than FT
Overall, I would not buy the boot again. The only thing stopping me from buying FT was the narrowness. But now they are wider, I would certinaly invest in them.
Spark notes: Kaos don't support the foot well, break easily. Buy FT
Sex: the most fun you can have without skis on.