Been listening to my T88k's this past week and man do these sound good. My most used IEM prior to this was the Westone UM2's. Those had great bass and instrument separation, but always sounded a little muddier than I would have liked. These offer clear sound, a very natural sound, with a bass that isn't muddied and hits. It has a thump like that of dynamic drivers. Overall the sound is a touch warm, with a treble that is present but doesn't extend too far. At first, it was a tad bright for my sensitive ears, but after a couple of hours, my ears became accustomed to them. I've demoed top of the line iems (SE846, IE800, Zeus XIV) and I would say that these gave me a similar instant "wow" emotion to those other iems.
I was rather surprised by the vent as most pictures I have seen online do not show this feature. The nozzle bores are also not the cleanest as they are pretty inconsistent between the left and the right, but it does not seem to affect the sound.
The silver hole. I've read on head-fi that previous iterations had a metal nozzle and I believe some people also had non-molded resin shells, so leads me to think that they're still tweaking the t88k models or something changed along the way...