Dont have an answer to your question but wanted to pass on a thought that I found helpful when reading about this in the past:

As a multiboxer, you have a really great opportunity to completely destroy dailies and make immense money through those means. When running multiple characters, I really think its more worthwhile to just do dailies etc (even run dungeons and DE stuff for materials to sell). Ive chosen to just go with non gathering professions on each of my chars and then just AH for stuff.

What I just said is totally irreleveant if you a) enjoy gathering and want to do it regardless of difficulties b) dont want to AH for materials , just wanted to pass the thought along.

Have a great day and good luck to you.