Re: 9.5" radius = Flat or Staggered?
My favorite singles to go with a humbucker in an HSS guitar is Fender Fat 50's, but since many HSS guitars have flat radius necks like 12", flat poles would make more sense. I just looked at the new Fender Showmasters, which feature a Duncan JB or 59 along with Fat 50's. The 2005 ones have flat poles, while the older Showmasters had Fat 50's with staggered poles. I guess Fender addressed that issue.
Me? I could care less. They all look and sound fine, as long as you've got the height adjusted OK. That's one thing I'm not that anal about.