Jeff - I've always wondered if you could run into the infamous HSA (mostly myth at the homebrew level I know, but with too much recirc in this way???). I may try a modified, hillbilly RIMS one of these days to see if there is a discernible difference, since I just did an ultra careful, no splash, rack to boil kettle to see if it results in any discernible difference.
BTW, I have a neighbor who does the drain and pour method while applying heat to a mash that is stepping up through steps or just being boosted to correct mash/mash out and he says he gets no problems doing it that way. And his beers are really good, too.