Was using a DC X-11, DC-13.4 and DC-13XL in rotation about 12 months ago.
Not impressed with the X-11, sold them to a student who liked them about 3 months after I bought them.
They were too light, not enough passive noise reduction and not enough clamping pressure - no good for Aeros! I did like the phone interface and they were very light and comfortable. I can't say you would forget you're wearing them - if they are allowing noise in and/or falling off during a slow roll, you know you are (or were) wearing them.
The 13XLs are heavier but a much better noise reduction, espec when the batts go flat (which my camera operator says they do, very quickly, on the BOSE). You have the best of both worlds: excellent passive headsets in the 13.4's
PLUS an ANR function. Plenty of life in the 9v battery too.
My mate took the -13XL's back so they could go to Antarctica and meet Peter Garrett, so now I'm back to my 13.4's. 30 hours /week in a C206 has me certain I'm going deaf
so... anybody want to sell their DC-13XL's?