Nic, I think you should keep quenc as GPL. That was it's free as in free speech, and nobody can make a profit by using your work (as can happen with some other licenses such as BSD). Nothing prohibits you from having a separate license with your code (and any code contributed under these terms) which allows specific commercial reuse (which you approve beforehand, rather than some megacorporation using your product in its set top box or other commercial product without your permission).