Well, I did some listening tests yesterday evening. The DIY Gotham cable is brand new (no burn-in yet) and if I should describe my impressions when I've first put my cans with this new cable on my head I'd second most of your finidngs:
* Overall the sound becomes more 'solid', more projectile, and more weighty. - Exactly what I've witnessed.
* BASS impact has been become more prominent. Faster attack and umph! Bass has definitely improved in every way, quality and quantity. - I was really surprised how prominent bass impact became.
* The cable somewhat makes the phone more musical - its very difficult to describe. - Exactly what I've witnessed. It was like adding some grains of HD650 sound to K702.
* However things are rather different on the treble - it got a little recessed. - This is also true, maybe it will get improved by time after proper burn-in.
After spending a few years with the stock cable I am not sure if I really like the "new heavier sound" of my K702s. The cable surely needs more hours to get properly burned-in and I maybe need to get used to it as the change in sound was much bigger than I've expected from very cheap and affordable cable like this. When I've put the stock cable back the sound have returned to lighter and airy presentation which I am used to ... I know habit is a second nature.
But one thing is for sure, there is something about these cables.