Even the experts who shoot sxs will tell you that it's not really a sxs game. And I don't think a modern sxs, purpose built for high birds, is going to take a back seat to a Parker.
I say that as someone who's never shot driven birds with anything BUT a sxs. More on the order of the old standby Brit game guns, for that matter. Those sub-7# guns work fine on birds out to 40 yards or a bit more (for those capable of making such shots), but sxs don't seem to do as well on the really tall birds. Just like you don't see very many top notch Sporting Clays shooters using them--even guys who really like sxs.

Tim, I agree with your sentiments about a lot of very tall birds just being "pricked". As does Vic Venters in his article:

"Moreover, a high pheasant gun does not necessarily make a high pheasant killer . . . Arguments rage pro and con in Britain's sporting magazines as to the ethics of presenting birds at ranges where many are only 'pricked' if hit at all . . . The driven game gun has changed much since 1914; good sportsmanship has not. Birds are living creatures; clays are not. Practice and shoot within the limits of your skills, whether your barrels are side by side or one over the other."

I find that very well said.