Chef -

Sorry to disagree, but none of the top civilian bands wear spats. SFU, Field Marshall, Shotts, 78th, SLOT, etc. Jackets, vests, and solid colored hose. As far as pipers are concerned, there's "no 1" (plaid, doublet, spats, horsehair sporran, etc.) and "daywear" (jacket, hose, day or evening sporran, ghillies, etc.). "No 2" isn't a widely used term. In general, no 1 is for parades, "daywear" is for the competition circle. The only legitimate competitive band in the military is RSDG, and they wear daywear on the field. Even then, they're not really a "top" band.
As for piping in the US, I can't think of ANY band in grade I or II that wears spats. If they do, its with plaids and doublets. Spats/hose tops and button down shirts tend to be the domain of street bands.

As to your second point, I wouldn't Harry Lauder as representative of traditional Scottish values. He was a hyperbolic "stage" Scot, and I think most would agree that he was more vaudevillian than an accurate representation of a typical Scot. Thats sort of like using Charlie Chaplin as your benchmark for modern men's style. Doesn't apply. Andrew Carnegie was a Scot, and I've seen him in trousers more often than tartan.

I'm really not trying to be rude, just stating an opinion and why I think it's valid. Oddly enough, a very similar discussion is going on now on the Dunsire piping forums.