I've used both though I ended up with the Dime CFH after my Demon broke. From what I've read here and elsewhere, I think now that I just got a dud.
The impression that I got from the Demon was that it was more of a growly type of wah. It can keep the bottom end on it's own with the low control, and being able to fine-tune the two ranges is a great feature as well. It can also operate switchless or switched, though the switch is on the side. I can actually imagine that being quite useful, for example: keeping the expression pedal in one place (or back all the time) and not having to disturb it's position to turn it on/off. You can adjust the delay time for the switchless mode using an outside knob, and if you have a coin, you can adjust the spring tension and pedal friction quite easily.
The CFH's main sound is that of a scream, compared to the Demon's growl. It does tend to loose some bottom end but that can be EQed back in (from the amp, or another effect). The advantage I like about the CFH is the fact that it has 6 heel frequencies (all listed in Hz, in the manual), plus you can
separatly adjust the pedal's sweep range. It's probably a little harder, physically, to adjust the friction on this pedal, though I've never actually adjusted mine.
Both have Q and volume adjustment's so that there is no volume loss when turning on the effect.
If you want to hear some serious fuzz/wha listen to: [Invalid or Expired Link Removed]
It's 14.1MB/10 min's long, but it should give you some idea of the CFH's sound. Note though, that it's Fuzz -> Wah -> More Fuzz. The first fuzz is a COSM model of the Big Muff Pi, and the 2nd fuzz is an EHX English Muff'n. On the model the gain is cranked, and on the Muff'n every thing is cranked including the bass, cus both the 1st fuzz and the wah lose bottom.
Hope that this, in some small way, helps
QUICK EDIT: hahaha, didn't realize that youl'd already owned one

Anyway, the info will probably help someone

, but I'm sure the reviews of the Demon will help you compare. The bassic Q to ask is: Do I want a deep, growly wah (Demon), or do I want a more high-end, scream-like one (CFH)?