To anyone that wants a .280AI, I say "Go for it." Never mind that I say the same thing to anyone that wants a standard .280 Rem or 7mm Rem Mag. There is nothing "wrong" with any of the choices.
As BobinNH correctly points out, though, they are not the same, nor can they be due to differences in case volume.
To those that suggest never exceeding published maximum loads, I offer this bit of caution - In 31 years of reloading I have come across several instances where published maximums were too much for my rifles. Not "blow 'em up" too much, but very short case life, flattened primers, loose pockets, etc.
My 7mm RM is a case in point. Something in my 7mm RM chamber causes a light 1/2" long scratch on the case every time a case is chambered. As a result I can easily tell how many times a case has been fired, or at least chambered, simply by counting the scratches. Using data available in 1982 I found I was getting 4-5 reloads per case before the case head would separate. Backing off the load enabled me to run 18 reloads before a case head came off. These days I use different powders (primarily H1000 and IMR7828SSC), get velocities I am very happy with and case life is good and long. And yes, my current loads slightly exceed the published maximums.
One of my .308 Win rifles had a similar problem with max loads - very short case life. Although it was extremely accurate with virtually every load I tried in it, it couldn't begin to compete with my .30-06s in the velocity arena due to lower case volume and even the max .308 loads were too much. (I ended up solving the "problem" buy selling my two .308's and buying an AR.
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My .280 Rem is a Ruger #1 and even with its 26" barrel it is no longer than my 7mm RM with its 24" barrel. While the longer barrel helps velocity, that help still doesn't bring velocities up to what I get with the 7mm RM. No worries, says I, as I like the .280 for what it is - a very capable cartridge in a launch platform I had drooled over for many years. That the .280 Rem launches the same weight bullets slower than my 7mm RM is of no concern at all.
To those that want to try to turn a .280 Rem or .280 Rem AI into a 7mm RM, I suggest reading up on Boyle's Law, then getting a 7mm RM. You can always download it to .280 Rem AI or .280 Rem velocities or even 7mm-08 velocities if you wish.
