The only thing varmint bullets are made to do is turn animals into confetti, best used for gophers and rabbits.
I havent shot 243 so I can only speculate but when choosing bullets for fox, coyote and bobcat with 223 I ended up loving the 65 SGK over the other multiple varmint loads I tried first.
I'm comparing small fox and big coyotes with 223 vs. coyote and small deer with 243 so I'm guessing. My problem with 223 and varmint bullets was if I had a good strong load that would perform well on coyotes then smaller fox size animals would be destroyed with huge exits, and the varmint bullets would fail on coyote shoulders if you made quartered shoulder shots. So I would expect a 243 Win varmint bullet loaded for deer to explode a coyote, maybe that wont happen but I would expect that bullet to completely ruin a quartered deer shoulder and likely not lethal. A 85gr SGK on coyote from 243win sounds pretty mean too but the performance of the 65SGK on even young small foxes is impressive, most exit wounds are hard to find.
But the Sierra Game Kings are very frangible explosive bullets on their own, the 65gr SGK from 223 even fails FBIs 16" minimum penetration in gel tests from short or long barrel because they are so explosive.
In the long run, hunting vs. Varmint if tested in a variety of targets and conditions my opinion is that the varmint bullets will be a handicap, the hunting bullets will always be more versatile and reliable... except if youre measuring prairie dog mist.