I have had Al's pair of 4070's for over a week now (thanks again Al!). First off, I have had a heck of a time getting a fit. (The weight was fine however.) The only way that I can get any kind of "seal" is if I angle the headband towards the back of my head or use my hands to push the pads against my head. Obviously, both of these situations are not optimal so you should probably ignore anything I say from now on. Basically, the cans just aren't doing anything for me. I've spent some time, going back and forth listening to 4070s and the JH13s. There is just really no comparison (for me). The 4070s are technically pretty good, except maybe for the bass, but when I put on the JH13's, it is like I walked into the room where the music is playing instead of listening in the hall. I am sure that a lot of this has to do with the bad fit so, again, please ignore everything I am saying.
This exercise has been interesting. It has made me think that maybe I really should be getting a pair of JH16+3A (and keeping the JH13s for portable use of course). Hmmmmmm.