I'm just an Internet guy, and I have some experience but not what I'd consider a lot. Nothing I say carries much authority. With that out of the way.......
I have now shot enough 6.5 TMK into enough whitetails that I'm not worried about terminal effects. I have yet to catch one in a whitetail, which to me says that generally that bullet will catch both lungs on an elk, even at angles. Wound size is significant enough that no elk with that kind of hole in both lungs is going far.
One thing that seems to be forgotten at times in Forms testing is that the delta between how well you shoot between recoil levels widens significantly when stress is introduced. I have never had a shot opportunity on an elk that didn't have a stress element to it, whether speed, cold, breathing hard, awkward positions,etc. So I suppose you could also ask the question like this " Can I afford the deterioration in my shooting that more recoil brings in stressful shot opportunities" just like you can ask " Can I afford the perceived lack of terminal performance that I get with less recoil" ( emphasis on perceived, lol).
This is really getting driven home for me with my 223 on whitetails. I've now shot 5 deer with it using 69gr TMK. Other than 1 rushed follow-up shot on a deer that was 1/2 a second from tipping over, every one of those shots has basically went exactly to my POA, to a level I haven't seen in the past. I'm realizing that in the field, while my 10 lb 6.5 doesn't bother me at all, I still shoot that 223 to a level that makes me willing to often trade possibly not getting an exit for the ability to simply hit POA incredibly consistently. And when I do that the deer is usually laying 30 yds away, even if I don't get a exit and blood trails are less impressive.
All that to say, I think we undersell how much better we shoot away from the range with less recoil, and that should definitely factor into this discussion. I still love my 6.5 and carry it fairly frequently, and will be carrying it for elk 100%, but I can begin to see the data trend for myself.