Re: What heads have you tried on your Sonor Designers / Delites / Maple light shells?
Do the stock heads have an actual Remo logo or are they Sonor branded (or one of Remo's "UT", "UX", or whatever sublines)? If the latter, they are probably made from inferior materials and just kind of crap all around. Makes sense that they'd be okay on an 8 since that small of a head on a ply drum isn't really going to produce much sustain/tone, "real" Remo or otherwise.
As for your floor tom problem, it might be a tuning issue. Generally, I'd associate 'basketball'-like qualities to a high-tuned batter head. Try tuning both heads to an identical low-ish pitch, and if it has too much sustain (though with pinstripes, this might be hard to tell), tune the resonant head higher than the batter- I usually do a minor third on floor toms for that.
Thick multi-ply heads usually produce a lower pitch, but due to the muffling effect of the other plies, their sustain and 'rumbliness' is diminished. The difference between thick/thin single ply heads is basically that of dynamicism, or how well they open up. Thin heads do that easily at quieter volumes, but thick heads generally put out 'more' at louder volumes.