Wow, Michael, I like the fact you have done so much to bring light to some of these drums. I tend to look at the older, really cheap stuff, but you have opened my eyes to some of these. I guess my love for the older funkier stuff is because of it's coolness factor, not so much the reality of the sound out of the box. Thanks!
Let's face, most of the stuff I like is the real budget lines that were the Sears specials, and the K-Mart Blue Light Specials and J.M. Fields stuff, the PP and GP and SP of the day. And I love them, because they look good, not so much that they sound like a professional quality kit, as the stuff you have mentioned. Those kits you bring up are all solid mid-market competitors, and they should be, because they really all sound so good. I like the beginner stuff, ultimately because they look like the Slingerlands with some cool hardware that none of the American builders used, like the cymbal mount and holder on my bass drum.
As for the Birch shell, I agree with Michael, they don't have the same warmth, but are better for larger venues were you need the volume to cut through. Birch is a higher density wood that many other woods used for drums, so the resonance is more focused, with more projection and higher pitch because the sound waves don't penetrate the wood as easily as it does other woods.