Which one to buy or build??

Well if I go with the 450, I will for sure buy a reloader. You can buy the Grendel ammo without breaking the bank for hunting. But the 450 is higher. I think that the 450 would be a great woods gun and small to medium green fields. Hogs and big bucks would roll with a shoulder hit or tucked tight behind the shoulder.
And as for defense; who would want to charge a semi-auto spitting out 300 grain slugs that would knock down good size pine saplings. Which reminds me, I have to get back on my thurty thurty and Ruger 44 carbine. I,m back on track now, had a good looking woman distracting me. A mans got to do what a mans got to do, at my age, buy more guns. :101010:

I have hunted with 45 caliber, 50 caliber, and 54 caliber Thompson Center muzzleloaders using maxie-bullets with TC lube in the grooves. Back in the 70s and early to mid 80s I killed deer with all three calibers. I never recovered a bullet on a deer that I killed with them. Complete pass through on all .There was a big hole on exit. But like you said, not as much meat damage from hydrostatic shock.