Correct me if Im wrong but , Im assuming you had to modify cgminer to make your drivers or modified drivers work with it? If so, wouldnt GPL dictate you must share said source?
Also, I havent read this whole thread ... but is it correct to assume that your modifications and / or vnish's mods are part of the L3+ nh firmware / cgminer?  I dont know who wrote the original devfee threads part but yeah ... I think GPL requires sharing almost, if not all of this source.

I personally take issue w/ the designed forced devfee part. As in, Ive seen miners "failover" to devfee indefinitely until said miner was restarted, The fact cgminer wont even start up unless devfee pools are alive...    its one thing to have a devfee mechanic ... its another to potentially have it steel a majority of hashrate / prevent mining of folks miners at large.