I've got a Stoker that I use with Stokerlog and a Guru Cyber QII. I've found much to like in both devices, as well as a few really irritating detracors. Here's how I see the pluses/minuses of the devices and companies:
Stoker Pluses
True network control: I can plug my Airport Express into the Stoker Controller, and it feeds right into my Time Capsule enabled network. So I can see the Stoker on my iPhone, my Mac and my old standby Gateway PC.
Lighted cannon plugs: I can see at a glance if my fan is cycling propperly from the periwinkle blue light that comes on when the fan is powered.
Multiple plugs: I can control multiple devices from a single Stoker controller (maybe three?).
Cost: Stoker's much less expensive than the Cyber QII. For my own configs it was about $100.00 less.
Stoker minuses
Customer service: It's been beaten to death here so I won't rehash my own issues. But it's a huge minus when you have a problem with your system and it takes more than two months to get it resolved. Kinda negates the cost savings when you can't use the system you spent good money and have grown to depend on.
Probes: The Stoker probes and wires are flimsier than the Guru's. I stripped a temp probe simply trying to place it through the Stoker WSM eyelet because there was no instruction manual advising you should remove the silicon sleeve prior to threading it through. John replaced at no cost.
System specificity for Stokerlog: Yeah I know, I know. I could use my PC or install Parallels on my Mac. But, I'd rather not go the Mac to PC workaround route as it seems to be a lot of extra effort/work just for one application, and my PC notebook is a real dog, performance wise.
Guru pluses
Ruggedness: The controller is powder coated and supposedly water resistant; alhtough I'm not really excited about testing the water resistance of the device, it does seem very tight, with no obcious exposed seams or points for water ingress. The probes are firmly connected to braided steel cables, and the cannon plugs are nice and solid.
Temp control: Absoutely solid. Properly loaded, my WSM stays within about +-3 degrees as long as it has adequate fuel (not counting temp swings due to lid opening, of course).
User interface/control: The Cyber QII interface via PC is outstanding. I've got a main status page with tabular data for the two pits. along with a graph. In additon, I can choose a "recap page" that shows just the data for the two pits in a large, easy to read format or a graph page that shows only the graph.
Guru minuses
More expensive: About $100.00 than my Stoker with the setup I got. There are, of course, other Guru systems that are less expensive, but they're also less directly comparable to the Stoker.
Network control: If I want to use the Cyber QII PC user interface, I either have to plug into the controller via USB cable or use a wireless USB hub and stick device to transmit wirelessly to my PC. The hub/stick has limited range and is also pretty temperamental. I can get actual network control, but it involves hooking my laptop up to the Guru and using Mochasoft to access my laptop remotely. Haven't tried this, primarily because it requires Windows XP and my laptop is running Vista.
Number of pits controllable: Two max, as opposed to the Stoker which can control three (or more I think).
System specificity for controller: Same issue as Stoker. Won't work on my Mac, plus the USB hub/stick setup is also Mac incompataible.
Bottom line, I find things to like with both systems, and there's room for improvement with both systems also. Will be interesting to see if one or both address their weaknesses moving forward.