I batch sparge for all the reasons stated above. As to setting the grain bed, I use a little rice hulls and a fairly fine crush, then I run off slowly while vorlaufing. Probably just under 50% flow rate. Then when it looks reasonably clear I start collecting pretty close to wide open. Then I put a double strainer on top of my boil kettle and pour the wort through it to catch any husks that might have gotten through. I check my late runnings and they are always above 1.15 or so, so I assume the best as to astringency and pH....YMMV, of course.