Adding some jet fuel to the fire, I recently ordered and received a PVHES Shorty stem. Immediately noticed that it was a much tighter fit than the standard stem, but was able to insert it after warm up without too much difficulty. I did two 15 minute sessions that night with the PVHES stem.
The next day, I went back to the arizer stem and was surprised to find it much looser fitting than before. It seems that just two sessions with the ever so slightly larger PVHES stem was enough to noticeably stretch out the seal.
From the time I first received the solo2 and used it multiple times daily over a couple weeks, the fit has been tight enough that there was no wiggle, and I was able to pick the unit up by the stem with confidence that the solo2 wouldn't fall off. (Not that I regularly do that or anything, just using it as a test for tight fitting seal.) Now, after getting stretched out by the PVHES stem, my standard arizer stems have a slight wiggle, and loose enough that a fully hot solo2 will fall off if lifted up by the stem.
It's all still perfectly useable, and the fit right now is more ideal than before. This slightly looser fit allows me to more easily remove the stem between hits if I'm being leisurely and don't want to keep cooking it, which is my preferred style. But I'm kind of disappointed that only two sessions with a slightly larger stem was enough to so noticeably, permanently alter the seal. I certainly don't want it to get any looser than it is at this moment, which is making me afraid to use the PVHES stem again.
Separate note, I'm also kind of disappointed in the PVHES Shorty stem altogether. The thing was expensive, but I picked one up anyway as soon as it was in stock, just to sate my curiosity if I'd like it better. The shorty stem is supposed to be a smaller bowl. However, the bowl is merely 30% shallower while maintaining the same diameter. Thus the minimum quantity I can pack into it is exactly the same as the minimum I can pack into the arizer stem, so I really fail to see any advantage to the shorty over the regular bowl. Yes, the herb sits a little deeper in the oven with the shorty, but there's no advantage to that I'm able to detect.
What's more, the 'micro-channel' grooves that supposedly allow for less draw resistance are pretty dumb. The design allows outside air to enter from above the unit, into the oven cup, and then back up through the bowl and stem. Since that additional air is coming from outside, it's significantly cooler than the air that travels the intended path, from the intake vent, past the heater, and up through the oven. So while yes, I can inhale more air with less resistance, the real result is that the cooler outside air mixes with the hot oven air, and requires running the solo2 at a 10-20 degree hotter temp to achieve the same vaping effect. So not only are the microchannels pointless, they actually seem to decrease efficiency. I know that these things have been around for years and these observations are super late to the party, and I probably should have done deeper reading before wasting $25 on a stem that permanently altered the stem seal fit of my unit, and that I'll likely never use again unless all the others are broken and it's the last option I have.