Several months ago I got a Dakota Model 10 in 280 Remington. I had wanted a 270, but got such a great deal on a really nice rifle, so I bought the 280. Now I'm glad that it's a 280, mostly because of the better bullet selection in 7mm diameter. Also, heavier bullets should do better in this cartridge than in the 270, should I decide to go that route.
I have found that most everything that has been written in this post is exactly correct. Factory ammo in 280 Remington is pretty scarce where I live, but that's OK, too - I plan to handload anyway. Also, somebody mentioned factory ammo being loaded a bit on the light side, and I would second that, too. I tried two different loads, and found them both to be 100 fps shy of advertised velocities. ( I have a 24" barrel, so the discrepancy is probably not a barrel length issue.) The loads were the 156-grain Norma Oryx, and the Hornady 150-grain ELD-X. They both shot groups of about 3/4" at 100 yards, from a barrel that had a couple dozen rounds through it at the time. I also shot a big Oregon blacktail with the Hornady, which performed beautifully. ( First shot, at 286 yards, broke the spine behind the shoulder and exited. I shot again, and the lung shot finished the deer. Found that bullet in the far-side shoulder; about half the bullet was left. It looked just like the pictures in the advertisement.)
Anyhow, I plan to load the 143-grain Hammer bullets, and I'm going to start my loading project with H-4350. This is my wintertime project, and I'm looking forward to it. The guy at Hammer Bullets told me to expect around 3050 to 3100 fps with this bullet, which seems reasonable to me. For the guy who started this thread, I would say this : If you go with the 280 Remington, I hope you're a handloader. If not, the 280 AI that a few of the guys have recommended to you might be the better way to go. You will definitely have a better selection of factory ammo in that cartridge, and an extra 75-100 fps doesn't hurt a thing. It is not a 7mm magnum, but it is very close. So is the standard 280, for that matter. Either way, I don't think you'll be disappointed.