First of all, In your area ya might have good wild yeast in the air or on the wild grapes, never tried that one but the wild grapes are few and far between. (E-mail me a bushel or two this fall, wild grapes make great jelly.)
I don't know for sure if wild yeast would take over a starter or if the two strains will flourish side by side, don't reall make much difference as long as the breadstuff rises>
Very little have I found written on sourdough by micro-bioligists, which leads me to think that either MB's are lousy cooks, don't like sourdough or they don't know either.
What I have found though is that their is also bacteria in a starter, in fact 2 kinds, on turns carbohydrates 9into lactic acid, these are the same kind that sours milk. Then there is the kind that changes the alcohol that the yeast make into acetic acid. This is the kind that makes wine into vinegar.
The bacteria seems to be in either the flour or the air or both.
Beyond this we need a MB that can give us more info.
Try either method of wild yeast, but let me know what happens, I am curious. There must be some wild yeast in the area suitable for sourdough, the traildrives from Texas made wild starters. Don't know if they had good yeast or fair yeast and good bacteria since they all seemed to make quick breads with salertus (baking soda) and not yeast beads.
The SF starters seem to have good yeast, since they are famous for making yeast breads. But any starter I have know of that was brung to my area have died in a short time. For some reason they don't like it here.
The bread yeast ones I have made, the yeast gets weak but the bacteria stay healthy, I can make good quick breads with them but they lose the power to raise yeast breads. The Champ. yeast keeps going for a long time, my present one was started the day after Christmas. If I don't have a lot of time I bake up, throw away or give away my starter and just make another one since the yeast is only 50 cents a package.
My chap. yeast ones seem to need used and fed twice a week instead of once a week like others. One can keep a starte in the icebox and only feed it once a month, but it needs about 24 hours to warm and get active so one must think ahead.
They say in a freezer they will keep forever, but it takes 48-72 hours to get active when unthawed. That is why I don't try to save on long term if I don't have time for it. I need the space in the freezer and it only takes about 72 hours to build a new on with the Chap. yeast.