Situation is this :

My main is rogue and i have LW and JC as professions ( dps boost professions ), so i miss the gathering profs to level easily those 2.
Anyway i have 2 70 alts one with herbalism and alchemy ( which i wouldn't touch ) and the other with mining + BS.

The matter is :

Do i lose much in wotlk if i drop BS for skinning?
I am in a raiding guild and most prolly i will get gear from raids, what has BS of special to make it worth having over skin for a rogue?