Gee Johnkkraus, funny you ask...
OK, I just received the replacement balanced full range and bass dongle cables with Audeze ends a couple days ago and did a bit of comparisons tonight. I have to say I'm pleasantly surprised. I was very skeptical and some of my observations were unexpected.
First on my LCD 2.2, I normally use with a balanced DHC Nucleotide cable that Benjamin here made for me. This cable is a huge improvement over the stock cable. I recently got the Cavalli Carbon amp and they all work well together. First I tried just adding the bass dongle to the DHC cable and have to say the bass dongle had almost no effect at all to my ear. Then I swapped out the DHC for the MIT w/o bass dongle and the whole presentation was slightly more detailed, particularly in the highs. I heard more presence and better separation of the instruments. However, this was at the expense of body and weight. And the vocals sounded slightly artificial in comparison. Overall I found the DHC cable to be more involving and organic. It reminded me of rolling tubes, you always pay for an improvement in one area by sacrificing something in another area...
Next I tried the bass dongle on my HD800 with the Anax Mod and a PCOCC balanced cable Sonny over at Audiocircle made for me. This is a great cable, all my interconnects and speaker cables are made from this. First I played the same material that I had been listening to on the Audeze headphones and as you may know, the character of the HD800 is very different from the LCD 2.2. There was much more detail in the high end and the bass seemed seriously anemic, especially after listening to the LCD for a while. But when I added the dongle, WOW! The low end came alive and got real weighty, without interfering with the mids or highs. The detail remained, in fact it increased in the low end but was weightier too. That was a very welcomed improvement. I also noticed in "Sing, Sing, Sing" from the Swing Kids soundtrack, there's a section where there's some incredible Tuba and Trombone action, but the acoustic bass is plucking along as well. I didn't hear this in the LCD's with either cable or the HD800 until I added the bass dongle, so that tells me the dongle really helped not just add body, but separation and detail.
More listening to come, particularly classical and rock next... as it stands, I will be using the bass dongle with the HD800's for now!