Just used the metal stem for the first time. I've been using the glass stem since buying the roffu. The added conduction with the metal stem really hits different than the glass. Less flavour but a more intense hit.
Yeah, I have a very low tolerance and I'm effectively working with a lot of conduction and it's working well for me. I recently changed my usage for the better:
I used fill a capsule and over time take 4-5 sessions out of it over an evening (or beyond), at steadily increasing temperature to use it up, otherwise early hits would have me over-medicated and/or coughing up a lung. This was also sub-optimal due to getting different actives out of different heats early and late in the capsule.
I've switched to high-temp (310C/590F) full-extraction of a tiny dose instead to get the full spectrum it has to give. The tube of dosing caps lets me line up the sessions. It does occur to me the way I'm using it I may as well just use a conduction device as I'm not really getting the convection benefits. Sadly flavor is not significant at these amounts, but it's nicer than the end stages of a well toasted full load. I also do much less coughing and it's much easier to predict/control dose this way.
Below is actually a pretty generous dose for me of MA retail weed. Yes I know this is unbelievably small from some people's perspective. Doing 2 or 3 of these each evening seems to keep my tolerance constant and low level, while still giving pretty strong effects. For comparison, about 7.5mg-10mg of edibles gives me similar effects but for longer. Any time I've raised my consumption I find the pleasure tails off and can't be found again by increasing dose.
Also blasting like this at high temp keeps everything cleaner and I almost never have to clean the caps.
tl; dr: for low-dosers, completely consuming a capsule in one session is a good way to go IMO, so just fill the capsule with the amount you want to consume
right now and blast it.