I bought my first .30 HERRETT in 1976, and the second in 1980 (10" and 14" respectively). I have about two hundred formed cases, and I haven't made a new one in 15 years. The Herrett is quite a bit ahead of the .300 Whisper, at least in my 10" barrels...125 grain BTips at 1950 fps and 2225 fps respectively. That's a difference of 320 fpe at the muzzle. But that said, the .300 is far easier to load for than the Herrett, and unless you want to shoot game at much over 100 yards the Whisper is fine. Less recoil and report too, although in 10" barrels the difference is not huge.