I can't find this said anywhere in that thread (maybe I don't know how to use that site) nothing about any falling out, or saying vapefiend were difficult to deal with, I know you have had problems with vapefiend in the past but can't find it said in that thread.
I did see someone on there had one and had problems with it but I'm sure they said vapefiend sent them another one without needing the problem one be sent in (but I can't see that anymore, so could be I don't know how to use that site properly)
I can see that a couple people over there don't like it or maybe have problems with a proper seal, the adapter I have seems to seal fine and it works great (but I've never tried the muzzmod so maybe I'm missing something, guess I will have to make one at somepoint to see, and then also try whatever
@Ratchett comes up with for the crafty) i guess with any glass piece there is the potential for things to not be perfect (which when talking about something that makes a seal is kinda important) I would like to think that it's just a small number of qc issue units that slipped through (time will tell) but who knows, I think I've seen more positive reviews than negative, but maybe what
@Ratchett said means there could be qc issues.
Personally I've always found vapefiend easy to deal with, I've had things that weren't quite right and after sending pics they sent a new item out and I kept the old/damaged one no need to send in, and the one item I did have to send back cost me £3 for delivery but they sent me a free item worth £10 to make up for it, maybe I'm just lucky.
Anyway I'm not trying to rubbish anyone's opinion just share mine (which I will update after trying a muzzmod)