On my wife's and my 300 Weatherby light gun for 1000 yard matches, we have KDF brakes. If they didn't work so good, she couldn't take the recoil with the 220 and 240 gr bullets.
I have had or do have some of the other known brands plus some made by excellent gunsmiths and the dampening effect of the "KDF" seems to be best of ANY we have used to date.
I have a Veis on a Goodling 30 Mag also and the dampening effect is NOT as good as the KDF.
The important part of the brake instalation is to have the correct clearance around the bullet as it exits through the brake. If I remember correctly, it's .016" to .025" clearance around the bullet.
PS--As an add on as Jim just said, you can shoot much longer without getting a sore shoulder. A person can shoot MUCH more accurate with almost any cartridge that has a fair amount of recoil with a brake then he can without it. Another advantage to the LR hunter using a fairly light rifle with a lot of recoil is, with a brake he is more likly to see his own hits (bullet impacts) way out there.
I have a Weatherby .300 laminated stainless steel rifle with the factory Accubrake. Brake works well enough to shoot the rifle one handed off a bench without getting punished by the recoil. I installed a Vais brake on a .300 Rem Ultramag BDL, its not as effective as the Accubrake, but it reduced the recoil to where I can shoot from a bench without getting a sore arm. The Vais isn't as loud as the accubrake, I'm getting groups under 1/2MOA at 100 yards - so accuracy wasn't affected. I didn't shorten the barrel on the ultramag when I installed the brake. On my Weatherby they shortened it to mantain the 26" barrel. My velocities are 100fps slower than book values.