Completely agree Denny, just as I said over at the HBT efficiency thread.
No need to rest, no need to drain slowly. Just stir the crap out of it to make sure the sparge and grains are mixed very well.
I do a batch sparge in biab as well, mash, pull the bag, squeeze, combine with sparge water, open the grain bag, stir the crap out of it, pull the bag, squeeze again. By squeezing both times, you're reducing the extract remaining in the grain bed twice, which improves lauter efficiency by about 5-10% depending on your process.