Good input.
Why buy the mats when I can get them running missions though? And I can of course sell extra mat's for profit, as well as the stim's / adrenals / etc that I make from Bio. Without any significant credit-sink, what's the point in acquiring 5 million credits? For some, that's a goal and that's fine...for me, if there's no utility in it, I see no reason to shoot for that.
I agree it makes sense to leave an alt running Diplo missions for the mats; I get that. It's more about ease of use--logging off main, logging on alt, running missions, logging off, etc.
Appreciate the input thus far. There's no doubt slicing is a very easily managed credit source, and I definitely like that.