I’m glad you have yours, too, Daren, so we can make comparisons. Good observations. “Retro” explains some of the appeal for me. I need to get out my vintage Pianica 36.
I removed the top and bottom keys to take a look at the holes. The big ones are at the bass end. The Yamaha photo of the hole strip is distorted the round holes are actually elongated vertically (not sure what the term is, I don’t think “oval”), and the squares are elongated vertical rectangles.
Your comments incline me to create a hybrid of these two models, Daren, using the core of the P-37D with the P-37E enclosure, probably with a white keys exchange and maybe using the E’s black reed chamber cover. I do notice the added resistance while blowing, which for me is a negative. It must be the source of my difficulties in tuning the P-37E.
The holes concept is good, but it seems to need more work.
I personally prefer the more angular contours of the E. My wife Linda wouldn’t let me get the hybrid Toyota RAV4 (as it was not available in red — who can argue with that?). But I’ll get my way on this one.