Thanks for the responses. I pulled the trigger on my probes today. I made a pour-over of some pretty damn good Yirgacheffe that I roasted 3 days ago and spent some time talking with the engineers at Omega. I ended up taking a slightly different approach than the other mods I have seen so far.
I landed on an ungrounded SS type K thermocouple, 1/16" in diameter, and 2.5 inches long, rated at 500f, with a simple epoxy bead transition. This is essentially the same probe I used to make my homemade SCACE device, just shorter. I will use a 1/16th NPT by 1/16th tubing compression fitting (with a back nut and lock washer) to stick it through the back wall. Just drill the hole, stick it in and screw the nut on, no JB Weld needed. The whole compression fitting is just under an inch long, roughly half of it will stick out on either side of the wall. I will allow the probe to stick out at least a half inch (8 diameters) through the compression fitting which should eliminate any danger of "stem effect". The ungrounded junction with teflon insulated wires will eliminate any danger of ground loops. This fitting/probe works out to roughly 1.25 inches inserted into the drum, and 1.25 inches sticking out behind the drum with plenty of play to slide the probe in or out as needed for fine adjustments. I did all the math and took a boatload of measurements and unless I screwed up it should fit just fine.
It turns out that an ungrounded 1/16th probe has a response time of just under three seconds, the XCIB style 3 (the best I solution I have seen to date) has a response time of 2 seconds, so essentially both probes are pretty fast. I traded the slightly slower response time for the durability of the sheath and ease of mounting. I figure that with the thermal lag of that heater being around a minute, a 1 second difference in response wont make that much difference in controlling the process. That one minute thermal lag means you still have to do "predictive" profiling no matter how fast your probe is, 1 second wont make or break me.
What I am shooting for is durability, ease of installation, and ease of maintenance. If the probe ever needs replacement, just loosen the compression fitting and insert a new one.
I will post pictures once I get it all done.
Now just to wait for all the parts to come in........
PLC/PID'd Lady Silvia, Stepless Rocky, HotTop+TC4C-HTC