It's all working great so far but I think the fact that my lan cable is running right beside a 600 v motor cable may be at least partly responsible for the webservice issues I am having. We are giving the wireless a try on the project.
Do you think we would be OK for bandwidth on the SBC with the USB wireless adapter that came with the SBC and 3 Advanced Servo (8) cards attached?
This is the part of your post that got me thinking about it:
ISSUES: NETWORK LATENCY
The SBC runs a USB 1.1 bus. That gives it 12mbit of bandwidth for ALL USB devices on the SBC. That includes all of the phidgets, the webcam, and wifi. If there's too much happening at once, things will start to get delayed. This usually isn't a problem, you can normally get away with a webcam, wifi, and a few phidgets provided that you aren't hammering it with commands.