Mulling over muzzle break such as SSK Arrestor for .280JDJ or .30/06 JDJ. Can handle Contender in .375 winchester with no muzzle break. Would I be better off without and gradual build up tolerance and use full power loads for hunting rather than deal with muzzle blast of break.,years ago fired a .223 contender with muzzle tamer(not that .223 needed it) and muzzle blast was ANNOYING to say the least-very distracting.Thank you.

People will come down on both sides of this argument. When I get over the .308 Win. / .309 JDJ, I vote for a muzzle brake. The Arrestor is an excellent example. We need to be wearing hearing protection with every shot anyway, hunting or otherwise.

what about a detachable brake? That way you could use it at the range for extended sessions then remove it for hunting. That is my plan for my 338-06 if I find it unbearable to shoot. Before I make up my mind I plan on doing just what you stated about syarting off lite and see where I need to go. Just my .02

Welcome to the forum powderburner!!
I think the calibers you mention are right on the line. Some folks will do fine without a brake & some will shoot much better with one.
I'm assuming you don't have the barrels yet, so part of the question is if you want an integral brake or an add-on (removable) style. If you want integral you need to decide before you get the barrel. Add-on, you can try the gun without & change your mind later.
For me, with the right grip, the 358 JDJ was OK with top loads, but getting uncomfortable. Grips do make a huge difference. My unbraked 7mm-08 hurt my hand with wood grips, but is a pussycat with factory rubber. My 35 welen AI & 450 Marlin both came braked, & they are a pleasure to shoot with factory rubber grips.

I have a custom brake on my 300 WSM and my 6.5 X 284 and they are a pleasure to shoot! I put one on my .223 for two reasons.

1. I put a rifle scope on my pistol (6 x 24 Burris);
2. I wanted to see the "hit".

I know, I know, I'm sick...

I have the 8mmjdj 14" bullberry wood Tsob base and rings. It has the jdj brake which consists of 4 oval slots on the end of the barrel from 10 oclock to 2,You can shoot it all day.