Regardless of claims to the contrary, case capacity matters when it comes to velocity and case life. What a smaller cartridge can do a cartridge with larger case capacity can do as well, at lower pressures. Before I got my chrono (around year 2000-2002), I was shooting my 7mm RM 160g loads at .280 to .280 AI velocities, depending on the bullet and powder. This was because I was getting case/head separations after 5 firings when using max Speer book loads (which have since been reduced). My 7mm RM has a flaw in the chamber that leaves a tiny scratch in extracted cases, allowing for a definitive determination of the number of time a case has been chambered. After backing off a tad to current levels I started getting 18 firings before I got another case-head separation. When I first got my .300WM I built .308 Win equivalent loads, then .30-06 loads, then full-house .300WM loads. The reduced loads gave longer case life, as expected, with excellent accuracy.
My own opinion is if I want to get higher velocity, get a larger case. If you hate case trimming, get an AI or get a larger case and download it to desired levels. Or get a case trimming setup that makes it less of a chore, as I have done. (I modified my "T-handle" RCBS trimmer to run off an electric drill with a nut driver, allowing me to trim around 350-375 cases per hour, including chamfering and deburring by hand, depending on the case.)
Seeking the "optimum" can be an expensive rat hole. I'm getting good case life with my .280 Rem and velocities I can live with. More importantly, I get recoil my daughters can live with. To AI that rifle would provide advantages that are outweighed by the disadvantages. But that is for me - individual mileage may vary.
