Many of the statements in this thread are, IMHO, propagating what amounts to nothing more than hearsay.
Regarding House and the inverted "W", I don't honestly know if he ever taught it but I'd say that, if he did, it was long ago. I don't recall him mentioning anything about it in his now-dated book, The Pitching Edge which has been out for a number of years and is in its second edition. The inverted "W" is definitely not part of his current teachings. These days, House believes the throwing arm belongs to the pitcher and that a coach shouldn't mess with it.
Regarding House and scapular loading, again I don't know if he ever taught it. But, as with the inverted "W", scapular loading is not part of his current teachings. House believes scapular loading is something that happens naturally and that you should just let it happen. It's a non-teach.
Regarding House and questionable mechanics, you've got to be specific as to what elements you think are questionable. Then we can discuss them. If there is something beyond the inverted "W" (which he doesn't teach, anyway), I'd like to hear about it. (I'm aware of at least some of the issues the rotational guys have with House's mechanics model.)
Regarding Mills and his dislike for the towel drill, I think he spent more time and energy dis'ing the drill than it deserved. Really, it was just one of many drills out there. I guess that is sort of funny. But seriously, while dis'ing the towel drill may have originally been a way to take jabs at House, I think that is mostly history now. These days, I think it's not really the drill itself that Mills dislikes but rather the notion of spending time doing drills instead of pitching off a mound. DM can correct me here if I'm off base.
FWIW, I'll be re-certifying with the NPA in early November so after that I'll have the most up-to-date information from House.