I've actually read that article before I think, perhaps on Ricordia.org. It's a good article, but I don't like some of his methods, even though he's much more of an expert than I probably ever will be.
For instance he suggests using scissors to cut the mushrooms. This is just my opinion, but I feel that the crushing and tearing action of scissors do more damage to tissue than a straight, clean cut with a sharp razor on a cutting board, which would result in slightly slower healing time.
I didn't see any specific mentioning of cutting the mouth in the article, but I guess it is implied by this quote:
Certainly one rule that had applied to any mushroom I had worked with was that a single slice down the middle seemed to be the least intrusive and had the quickest rebound time.
So, maybe for Yumas cutting the mouth is the best method?
I still think the foot is the most important thing to cut though, and leaving the mouth intact allows you to feed one of the pieces sooner, which is always a good thing. But, I'm not an expert, or even close to one, so my opinions/ideas probably aren't worth much =P
When I have time (and enough back up Rics) for some experiments I plan to try some different methods out and I'll be sure to share my results with everyone.