My custom moulded hearing protection arrived; the cool thing is that the filters pop out so that they can be used as custom tips for the Crescendo DS11 which is basically the same thing as the ACS T15.
Now the ACS T15 currently sells for €50 more, so that already sounds like a very good deal, but reviews on them are scarce and mostly old.
ljokerl gives them high praise as do trusted reviews. Both also state that they are not as boring or purely analytical as a typical balanced armature IEM, especially considering it only has a single driver.
 
Truth be told, I do not like purely analytical headphones. My Philips Fidelio L2 gets the balance between analytical and fun just about right. Where would you think the DS11/T15's fall? are they fun for a BA in-ear only? Would I be better of buying a dynamic driver IEM and forget about the custom tips?
 
Also, any experiences with the ACS T15/DS11 would be much appreciated.

Update!
I had contact with the people from crescendo. Their customer support is very helpful. They confirmed that indeed the Crescendo DS11 is identical to the ACS T15 as crescendo are OEM'ing the T15. Only difference are the cables; the ACS' are kevlar-reinforced but the cresendo's are not. The cables are made by the same manufacturer though.