I've used SFX pads on the Cyclo. The work just fine, but the edges will get chewed up a bit, especially on the SFX-1 pads. The SFX pads are the right diameter, but because they're thicker and heavier and because of the Cyclo velcro backing plate design (the rubber "flap" that actually has the velcro backing allows some wiggle), they tend to touch when the machine is running even if you have them centered well.
The SFX pads work quite well, but as I said, you notice some edge wear, and some increased dust (from the foam itself as the edges break down).
Tort