I began using RWS No.11 caps in 1974, after my first trip to an NSSA Spring National Shoot. I have tried others over the years for both Rifles and Revolvers and went back to the RWS as the most sure fire and consistent. Consistency is a huge deal for accuracy.
Though I did a lot more reenacting with Rifle Muskets than live firing since 1980, and though I have done some competition firing with them, I also tried a couple other brands of Musket Caps and went back to RWS for the same reason as their No.11 caps. I always felt it more than worthwhile to pay the extra for RWS caps, even for reenacting.
Gus