If you aren't much of a regular shooter keep the .243. I love the cartridge. And it sounds like you'll maintain it well after everyone's admonishments. 'course my 760 is a .308 -- lol.
Originally I was going to say "let your BROTHER pick first."
This above all: to thine own self be true, And it must follow, as the night the day, Thou canst not then be false to any man.