So just put on the G-Cush.
I am yet to listen to anything with a great recording to test stage differences etc, however things I have noted so far.
The bass is not diminished so much so that I find it a problem in the least (and I can't stand bass shy phones)
They are no less comfortable, though I feel they will be more comfortable over long sessions. Yesterday I listened to these cans for about 5 hours while working and I found that due to the frame of my glasses that my ears began to hurt. Given it was over 5 hours this is hardly a complaint, but these pads hold the pressure well off my ear so this is welcome.
Really the only issue I can really see coming from these is I need to have the volumes SLIGHTLY higher, which will cause more noise out and may cause my workmates to kick up a stink, but we will cross that bridge when we get to it haha.
Thanks for the advice, all signs point to this being a good upgrade, sonically and comfort wise.