i have never used them in the filed, but i always used sf 7.0, never owned 6.0, its resampling w/ the anti-alias filter was really nice
but overall, for post-editing, like resampling and whatnot, i like wavelab 5.0 the best, no errors w/ dither and it resamples a TON faster than sf 7.0, but thats because the wavelab doesnt use anti-alias filtering for resampling
also, if ya need to post-show dither, wavelab 4/5 has the uv22hr and uv22 from apogee
theres pros/cons of each, but mainly lately, i use wavelab 5.0a if i need to use anything