I use D3, 1D,D300 S5.
Personally I own a 1Dmkll...its only 8meg....not a pixel peeper.
I can't tell the difference with filters as far as quality issues are concerned..
In all honesty I never use a filter.....might use a grad for landscape stuff if its too bright.
As for full frame....doing the job I do full frame is a pain in the arse!!! means we have to get closer
love the pieces of poo comment......my lenses are trashed...ha ha ha but still work perfect , if not a bit grindy grindy