Well, now that the dust has settled a little bit, here's where I stand:
I've converted the Datanab driver to IP connection, and it appears to be rock solid talking directly to the quatech.
I've converted the Ocelot driver to IP connection, and it appears to be rock solid talking directly to the quatech.
I've converted the OnQ ALC driver to IP connection, and it is definitely still have stability issues.
Next up will be the TRS RC-15 thermostat driver, I think.
There's some nice advantages to having the drivers on IP at this point. I'm still having some serious PC problems with my eventual WHS/CQC machine, so in the meantime I've moved everything to the kitchen PC which is on 24/7 also. With the drivers being on IP/port addresses instead of comm ports, the move over to another machine was painless. Also, as part of the troubleshooting process, I removed all the port redirector type stuff...so it's nice to be able to remove that from possible sources of problems. The downside is that I can't easily switch over to software that requires a comm port to connect to the device, like manufacturers software. I guess I could still install the quatech software for just those occassions.
I'm beginning to think that the ALC issues I'm having are the ALC's fault, as detailed in
this thread. I think I have a really REALLY picky or faulty serial unit. This thing seems to *only* happy being plugged directly into a PC, and as the thread details, not even really then. It shouldn't be that quirky, so maybe its something I need to replace.