I use Spyder controllers all the time - both unitary and VAV. The tool runs very slow (especially in debug) and eats a lot of memory (need at least JACE-6), but they're extremely flexible and highly versatile. The new Spyder tool is due to come out next month (we'll see). It's much faster than the old tool - I've been using the beta for a couple of months. The two best things about a Spyder are 1) You write your own network variables - pretty much whatever you want. 2) You can save applications you have written or even entire controllers to a Library and share them with coworkers and/or reuse them over and over again. If you write generic applications - for instance a VFD control loop with an input for static pressure, occupancy and setpoint, and an output for the VFD drive signal and start stop - you can save that application and then drop it into a completely different controller later on down the road and you don't have to write it all over again. All in all, I think they're great controllers and with the release of the new tool set for next month, they're only going to get better.
-Daive