Do you have a Classic UD? I know I'm not SirElton and I'm interested in his outlook on the subject as well, but here's my take. Simple glass stems are nice but I have issues with the glass being too thin (or silicone to smooth) for it to stay firmly connected to the silicone. After a bit of usage the silicone seems to not stick to the glass and the glass slides around and/or your silicone will slide off. The screens also get moved too easily or the glass will move your screen or move away from it. Thick silicone stems are really nice as they seem to provide thick heavy hits and for the classic core it fits firm and is unlikely to fall off (disconnect itself) from the heatport. Shorty GonG works well and great because of the height though the new gong yields good improvements, I believe I had a video in the T-Vape thread using the shorty, but no milk. Its very similar to the current glass stem Dave offers but isn't meant for the formed screen, it hits pretty airy but that is beneficial for bigger loads through water. The screen for the shorty is its biggest downside, I've had my incidents where I am attempting to stir and it topples on me, placing also isn't as great as the formed screen. I do wish there was a shorter current gong. The current GonG adds length and has a similar fitting to the shorty gong. It uses formed screens which are a huge improvement and allow for the ability to change the screen's position. TL;DR - ? Silicone encloses on the heatport more firmly than glass creating less excess air being drawn and giving more direct heat with less cool air, I don't believe silicone works the same on new/current models. Just my interpretation, I believe silicone stems to hit similar to nylon stems but with the ability for screen placement. On a side note, I use the GonG for DD more than for water, and it looks like Elton's stems with silicone are all using thick silicone, I eventually just cut more thick silicone to get smallers pieces to use them with the glass liners as they were more stable for putting in screens and holding the stem. I currently use Hammer OG stems with thin silicone for my UD.