As noted above, a big advantage of SVO is cost, since you're typically getting the oil for free and investing labor to clean it. Disadvantage is that you have to buy or build and separate, heated tank, related fuel & coolant lines, solonoid activated fuel selector valve and switch, and another fuel filter. Not a big deal but takes a little time and money.

If you buy biodiesel you just put it in the tank and go (although you'll need to watch rubber hoses, etc., for softening caused by the alcohol. Making your own biodiesel involves building some processing equipment and handling chemicals as noted.

I'm going to do both and swear off petro diesel just because I can.

fmb