Veggie oil really isn't much of a problem and it's seriously easier to to the biodiesel. Bacteria is not something you hear about much at all and then it's usually from someone who is a detractor of veggie oil. If you do a good veggie oil conversion, MidWest winters aren't going to bother you, I'm in Oregon, it doesn't mean a thing if you are prepared. Go find some SVO forums like
http://biodiesel.infopop.cc/6/ubb.x?a=cfrm&s=447609751