I have both the G930 and the G35... I love them. Gave my brother the G35's and am now using the G930's.
The macro keys can only be set for iTunes and other audio services (TeamSpeak, Vent (I think), Winamp, etc).
Sound quality is great, but not excellent. The mic sounds great!
Many people would recommend a pair of these
Amazon.com: Sennheiser HD555 Professional Headphones with Sound Channeling: Electronics
and a separate mic for sound quality.
And about the comfort of the G35/G930... I agree.. They can be worn for 7+ hours with very little discomfort.