These conversations always make me laugh...
I bought a .243 in 1980, when I was a youth (20)...I'm now 58, and have killed well over 200 deer with it, losing 2 during that time...I'm also 6ft 5 and weigh 240, nobody tells me that it's for "smaller" hunters...
The .243 is one heck of a deer rifle, I've killed too many to be told different...
My 2 brothers and their grown sons have .270s, a 7mm-08 and a .280...They all kill deer, how quickly is dependent upon where the bullet is put...Frankly my deer go down quicker than those shot by my brothers or my nephews, know why???? It's because I use that .243 year round for crows, groundhogs, coyotes, whatever...I can shoot the dang thing and put the bullet where I want to because of familiarity with the gun and practice...
In the end, that is what is most important...