Each brand has it's own characteristics and nuance. Not only the "bang" factor, but the size of the cup.
They all work, or they wouldn't be on the market.
Cap choice and what works best can be as debatable as powder choice, who makes the best car and what makes the prettiest girl.
All it takes is one bad experiance with caps that may have been improperly stored and a person won't like those caps anymore.
There are differances in "magnum" also, some may have a slighty hotter temp, some may have more volume.
The Bevel Brothers did an experiment with caps a couple years ago, and there are differances.
I've had my best luck with RWS Dynamite Nobel and stocked up several years ago, CCI Mag caps are a close second.
As capper likes Remington, I had a bad experiance with those 15yrs ago and stay clear of'm, :idunno:
Because of the little differances, changing caps will change groups on paper down range. Cap temps and charge are just another variable in the PRB load mix.