The -D holds E better and turns better. It has less of a stall to the left wing as well.
The difference is noticable if you fly the -D a lot and grab a -C. But if you fly the -C a lot and fly the -D you will only notice the lack of cannons and not the more forgivness of the -D. Just the way a mind percieves things.
And yes the -C wieghs more, not positive but I think it is somewhere around 600lbs more.
Booky