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.
With the way I recirculate, where can extra air be introduced? The return is below the mash surface, the pump is not adding air.
I pump to the kettle through the outlet ball valve and dip tube, so the dip tube is covered as quick as if I racked in.
Pilsners brewed this way in the winter stay in good condition to the end of the summer - when they are gone.
I guess you are right, but when I do the recirc during chilling, I get some foaming, at times.
If your light lagers are holding up for months, you don't have stability problems. Like I said HSA at the homebrew level is said to be a myth. So, I may have to give it a try.