I agree there. I can say from experience; many things labled as Gibson, Fender, Martin, or even Sony, Panasonic etc. are built by other companies, and they private lable them. We do it at my day job. We manufacture Jewelry cleaning products. All those jars you see in stores at the jewelry counter that say... whatever store name, is actually made by us, but we put private lables on for the client. That's why I never go by the name on the headstock, except for certain instances, like an Amerian Martin D-28. Amps are even more like this. They say Fender, Marshall, but if you take it apart, you'll find a lot, in some cases most of the parts are made by other companies, especially if they're made in another country.

The PRS strings are made by D'addario. I don't think they are the same spec as XLs but they can't be very different.

And I only used them on the Strat as I had a load of them in my kit box. I wouldn't have bought them for the Strat.