I returned the unit... but still want one. I was just asking if it could work because I might buy one again some day, and probably would like to have the option of an adjustable stem without worrying about damaging the glass.
I've got stems and GonGs that have been in use for almost 4 years now, and have read every page of this thread (and written on a good many). I just took a look at some of my older ones (with frosted GonGs) and newer ones (all at least 1 year old) under bright light with naked eye, 10x magnifying glass and 30x scope. Nothing at all was visible with naked eye, 2.0 reading glasses, or 10X magnifying glass.
I saw a few micro scratches at 30x that went lengthwise that were probably caused by screen insertion/removal. Even this was much less than expected as each of the 4 pieces I looked at (3 GonG, 1 stem) are in the regular rotation and I swap screens weekly (if that long). Of the 4 pieces checked, 2 of my favorite GonGs were the only ones with any scratches at all. I'd estimate the older one has at least 500 loads thought it, so probably 100 screen swaps and even more adjustments.
A few scratches = 3 of varying lengths on the oldest GonG (not all the way top to bottom but random streaks), and one on a GonG about 1 1/2 years old. All scratches seemed to be a one time thing, not from repeated digging by metal. After reading your posts and never really thinking about this I was very surprised to not see fine scratches everywhere up and down all of them. I stretch screens so they stay tight and am pretty rough on things as far as screen on glass goes. I like those puppies to stay in place unless I want them moved. And, can take a little force to get them going. Plus, I take advantage of the GonGs I have that let me slide the screen in from the GonG end. Much easier to get them in that way!
So while possibly a legitimate concern, it doesn't seem to be warranted. And, it kind of makes sense. The soft metal of the screens isn't hard enough to do much damage to the glass. I don't even know if the scratches seen are from screens, aggressive cleaning or scraping wand hash (I suspect from scraping, but who knows for sure?).
Might have been that the particular glass you had was faulty. But, did you see any damage? I can't recall anyone else having an issue with this nor doing much damage with screens. The most reported problem with stems/GonGs is that they break when dropped onto a hard surface (ceramic floors being the biggest problem).
As far as the rest, it seems like you're engineering a custom vape of some sort, or looking for competitors to merge and make you the perfect vape. Perhaps you would be more comfortable with a glass screen or could have OGB (or another blower) make something custom that would fit on a nano. As an alternative, degummed hemp fiber could be used as a screen instead of the normal metal baskets.
For me? I'm good with the adjustable screen system as it is, and love the ability to adjust - even if I put my screens in at the exact same depth every time. My only gripes are having to stretch them to keep them tight (could also replace for cheap), what a bitch it can be to get them into the glass, how they will poke your fingers while futzing with them if not careful and how quickly they get dirty enough to affect performance. But, don't think much can be done about any of these issues. And, none are really that big of a deal.