Currently, using AK SE180 with SEM 1 (ESS 9038 pro). If I want a little extra warmth, I would use the SEM 4.

Have been using it for the past few weeks, no fit issues. Can wear it for hours without any discomfort. The shell is smaller compared to Helios.

Go for Crimson!

It's pretty challenging at first but there is a technique for it. Find an angle to slot one part of it in, then you twist it (try finding a youtube video on this, pretty abstract to describe it in words). Enjoy your new iem, it's awesome.

Hi, It is not vented. Have been using the Crimson for a week now. I do not experience any discomfort due to the pressure build up or even the fit after long listening sessions (3-4 hours).

Lucky enough to get the last unit of Crimson from zeppelin & co today, number 14. Super awesome in every aspect. Bass mid treble and technicality. Tried Singularity in the shop as well, pretty impressed by its performance too. Seems like I cannot upload photos directly from my phone.