I actually was wondering if it made a difference using the right versus left hole by the charging chute (MET). I assume not.

It depends on which version of the Quest you have. Older Quests had both heating elements on the bottom; so you could use either hole for MET. Newer Quests have one heater on the top left and the other on the bottom right. If you use the top left hole for MET, your temperature probe will be very close to the element; so I use the right hole. I didn't test the left hole to see what the difference in temperature would be.

Dave,

I found that when I charged the M3s with lighter loads the standard ET port on the left side registered closer to the BT probe temps, which I attribute to the fact that the BT probe in that situation is not in contact with as much of the bean mass as it would be with heavier loads. In that case the upper right MET probe seems to provide better profile planning responsiveness. When I roast 200 to 250 gram loads, however, there is a greater distinction between the temps recorded on the BT and ET probes.

Another confounding issue is that the stock probes are thicker than the 1mm probe you insert into the M4 vented cap bolt. The 1mm probe is much quicker in response time. Using a thinner probe in the ET port gives a faster response time, but the stock probe is a bit sturdier and that's what I've been using.