Are you planning to reload or buy factory ammunition? Either way a 6.5 prc to start and later rebarrel is probably the better choice especially for a tikka, since you were originally considering the 6.5 SAUM the 6.5prc is a good choice, the availability of factory ammo is very nice from hornady.
Meaningful is such a subjective term. Many people will argue yes, and many will argue no. Does it perform better on paper past 500 yards yes. Does it have less energy up close also yes. You honestly can’t go wrong with either one.