There's all new MPEG-1 and MPEG-2 encoding, from a different vendor. Charger won't work in C6, but you won't need it since full MPEG-2 comes bundled with it.
However, the interface isn't integrated like it was before. Also, there is no way to set peak data rate with 2-pass VBR.
My Book:
http://www.benwaggoner.com/books.htm
Cleaner e-book:
http://www.ebooktech.com/shopping/shopexd.asp?id=279
Cleaner Tutorial:
http://www.saferseas.com/navseries/adclean.html