Having seen a lot of poor shooting/bullet placement from recreational stalkers using the .243, when i have been taking folks out stalking on the open hill in scotland, i wouldn't recommend it for shooting reds. Roe and fox it is great, i shot my first roe doe with a .243 but i would never own one. The rifle of choice where we were based was the 25-06...nicely in the middle of the 243 and 270. Ideal knockdown on red, roe, sika and of course the estate foxes too I still shoot mine 10 years on and love it.
The big gun argument is ok but i've seen a red hind get shot with a .300 win and that