There's no debate in MY driveway.There is a raging debate in the automotive world about introducing all new fluid into an old transmission. The theory is that it can crap out an older transmission that is on the last leg of its life journey.
Depending on use, changing at 50K is too often.If it was my truck since brand new, I would have probably done a full flush using that method every 50k or so... When I throw in a new transmission, I will definitely maintain it that way as well.