I have a cyberqII and like it a lot. I have a Primo oval xl and I have the 10cfm fan. No way I would get the 5 cfm. You can always choke the 10 down, you cannot increase the 5. Pretty simple there.
It claims it is waterproof, but I built a waterproof box out of a rubbermaid to hold it when it is outside (works great...cooked right through a 14 inch snowstorm and numerous rainy nights). I would not leave it alone outside when inclement weather is on the horizon.
The biggest difference between the 2 is how you can remote monitor them. Plain and simple the Stoker is better in this regard. It has a built in web server. The CyberqII does not...it connects via USB, which is an inherently inferior interface. CyberqII claims it can be used remotely via wireless USB...well, I have not seen a single wireless USB hub that will actually work through walls or anymore then 10 feet away from the cyberq (and I have tried a couple of them). There does claim to be a super charged wireless USB...I cannot seem to find it now, but it was about $250 bucks, so I did not try it. What I do is run a 33 foot (from monoprice) USB extension cable from my family room out to the deck to the cooker and it works well for me. I have not had a single issue with the USB cable or operating the cyberq from inside. If you want to be able to control the cooker via remote location over the net, or even with your PDA, then the SToker is what you want. I like the Cyberq, and will continue using it, but if I could do it over again, I would go the stoker route. (the main reason I did not go that route is because he was backlogged about 3 weeks when I wanted to buy and I wanted it right then!).