I did all the steps to it except for the velour top mod part because I only have one set of velours (which I really like) and don't have access to another set if I had messed something up cutting them.
I liked the jerg mod even thought the difference in sound was slight for me, they made the sound a little bit more airy which I kind of liked.
I found the comfort didn't work for me though. Taking the foam rings out of the pleather pads makes them super pliable and takes away pretty much any support or cushion. When I put on the headphones with the jerg mod my ears are basically pressed against the drivers and for me that doesn't work. Like I mentioned in the jerg mod thread, this is without the velour top mod which I'm sure would help with comfort. Based on the experience I had though I don't find that it would really be worth cutting up my velours to do it, the difference wasn't really substantial and I like the sound quality with the stock velours.
As for the pleather vs velour, I prefer the velour for sound quality as well as comfort. I found the velours a bit stiff out of the box, but after a couple of weeks they feel much softer. To my ears the sound has a bit more impact and sounds a bit warmer, the pleather sounds brighter. I really don't like pleather or leather pads, they get warmer much quicker and I tend to sweat in them, not the case with the velours. I'm usually listening for long sessions so comfort is very important to me.