Get the 26" barrel and try it out. Easy to cut some off but hard to add later. My current 7RM has a 23" barrel and it usually doesn't get to published velocities with out a strain. I suspect it is the fabled slow barrel rather than the length. Or lack of magic powder and secret loading knowledge. When I re-barrel I will probably go 25". I have lighter 280AI and 270 WSM so lots of overlap.

270 vs 7RM sounds like a whats a .223AI? type post.

For deer size game probably not a lot of difference. For Elk and similar the 7RM gives me more confidence.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli