Ok, I have put about 20 hours or so on my TF 18's, even did a little comparison to a couple other of my favorites, the UM3X's and M50's.
what can i say, and I'm no audiophile, nor am i as good with the jargon, these things hands down out class anything else i own.
My previous favorites, the Westones, now sound aneimic compared to these. They still have that nice balanced sound, but it is literally like going from an old CRD television with a DVD player to a new high end HD 3D LED playing a blue ray. There is just so much more that comes through. The mids are rich (and that is an understatement), the lows go lower and are much more textured ( think i already said that, but its worth repeating), stereo separation is much better and sound stage is unreal for something thats' sound is eminating less that 1/4 inch from my eardrums. Highs seem to be just right, no simblance, not overbearing or muted, just about right.
If there was an area that i thought could be a tad more present, it would be the very upper spectrum of the highs. With the exellent EQ on my sony X or rock box'ed clip, i can add a tad there and seems a more lively ( although subtle) presentation. This is most likelly the small void that the 8 driver upgrade fills. I still dont think i made the wrong choice though, as the eta 2 super high drivers all but doudled the cost of the upgrade, pushing the cost/shipping costs just shy of the mirricle or westone flagship range.
listening to them now through a PIMETA V2 amp that i just completed, using fairly high end components in the amp, and it is just amazing. Not that these need an amp, the other nice part about these is that they sound very, very good straight from the headphone out of any of my players , the sony, clip, or Iphone4, the latter being the one i use the most.
These beat the M50's in just about every way possible, except possibly aural impact on bassy tracks and high volume tracks where the large M50 driver actually adds some outer ear virations to the mix, but thi is a given, and is less a "sound" thing than another sensory input, SQ wise the TF18's are better in the low registers.
Anyone out there who is on the fence about getting the 6 driver upgrade to a pair of TF10's, just do it. As far as i can tell, there is nothing of my old TF10's left, these are wholy a different and much better animal than the blue plastic things i sent to UM. As for the 8 driver upgrade, if you can get a good deal on shipping (witch i did not, Fedex charged me $100.00!) if you can afford it i say it is probly a small step up. But If i recall, it is over $700 for that option, and with shipping plus cables you could probly just order a set of miricles or other ~$1000 IEM. don't know if they would be any better or not, but if i recall correctly, MaoDi sold his TF18's after he had a st of mirricles made ( correct me if im wrong here MaoDi...)
Now I have to figure out what to do with my UM3X's. somehow i think a simple remold will just not do. but unless it has changed, adding 3 or 5 drivers to the westones is fairly expencive........ hmmmm what to do......what to do
do update more on the performance changes 
