Many old school hunters don't think a 243 AI or 243 win is sufficient to hunt deer. Some would not think of even using a 110 gn 270 bullet to hunt deer either. However, others have realized that with good shot placement it doesn't take a cannon or the heaviest bullet per caliber to properly kill a deer at short and medium range. I belong to a local wildlife club and one of the gentlemen in the club is the local school's shooting team instructor and he switched to a 243 for his go to deer hunting rifle for several reasons. Many younger huters and women are given a 243 as their first deer rifle due to it's softer recoil, excellent accuracy and capable killing power. This is especially true when using the right bullet at the right distance. In the area where I live most deer are shot at less than 200 yrds and the deer here are nearly always under 200 lbs, most being under 150 lbs.
Now, with this website being called "Long Range hunting" and not called under 300 yrd hunting, I could see why a true long range shooter/hunter might not feel that a 243 is sufficient. The heavier bullets from a larger caliber will carry farther downrange with more accuracy and energy and be less affected by the wind. But under 300 yrs and maybe with the 243 AI with it's higher velocity you can stretch that distance some, a 80-85 gn Barnes bullet will hold together and cause massive internal damage to a deer and nearly always penetrate the animal through bone or whatever. I mention 80gn here as the Barnes TTSX is 80 Gn and the TSX is 85. I prefer the TTSX as I belive they carry slightly better at range and open up a bit better. But then again they cost more. One downside with Barnes bullets, you get more copper fowling so I recommend a good copper solvent and use a 1 caliber oversize bore brush.
As to fowling, you might also checkout the use of boron nitride coating on your bullets whatever type you use as it seems to reduce fowling and doesn't have any negative side effects. Boron Nitride Sources and Application Procedures « Daily Bulletin