The age old question and quest for the perfect pelt friendly predator gun.
The 204 and 20Tac are just using different brass, it's still a 20cal.
I have friends that use or tried 204s, and we sell the hides. I can say that they have just as many blow-outs as I do with the 243 and 22-250
What i have found is that if you get a 22-250, with a 1:14 twist rate (typically in older bolt guns) and use the 40gr vmax load, not loaded for speed but for accuracy at around 3600-3700fps or less you will have the energy to anchor both animals. I have drilled bobcats, fox and coyotes at 50yrds without a blowout using this setup.
The challenge with a smaller gun or FMJ bullets, which can zip through and not achor animals or people, is that you will spend time tracking them. I want the coyote Dead right there (DRT) every time, or as close to that as possible. You can't sew a hide on a coyote or fox if you don't recover it.
So I will take DRT over pelt damage everytime. Sewing isn't that hard to do. I found that blowouts seem to have more to do with the shot that you are taking than anything. I can shoot a coyote on one stand at 60yrds and have a pin hole, and then on the next stand shoot and hit a bone at 100yrds and have it look like a Samuri got up there and tried to decapitate them.
I try to avoid the head on neck shots, since it makes skinning tougher when you hit a bone in the neck/high chest and get a blow out (common) I try to avoid headshots because scraping the scalp off the hide when skinning doesn't make it faster. I try to be patient and wait for the broadside heart/ lung shot and try to avoid the shoulders.
Last year I sold 30 pelts, and once you get it down, a hole here and there isn't a big deal. If you sew it right, you can't tell it was there.
Just my 2 cents and personal experience.