I found this thread yesterday, and it is a very good read:
http://forum.snipershide.com/snipers-hide-bolt-action-rifles/52833-caliber-choices-comparison-applications.html
A lot of long-range hunters (I'm talking about shooting coyotes at over 1000 yards!) on youtube are using 6.5x284. The biggest problem I see with these kinds of rounds is barrel life. Some of them only last 1500 rounds (the article linked above says 800-1000!) before the throat is burned out to the point where the rifle will only shoot MOA, according to many reports.
Now, if money is no object, then hey, why not? But for me, I'm always broke, and when I build/buy a gun, I want it to last me a long time. As in, forever!
I know, that's not going to happen.
It's taken me a while, but I'm slowly learning to figure out exactly what I want a rifle to do. That is, being realistic about my expectations, and what I WILL do with it, not what I MIGHT do with it. When I bought my first rifle, I wanted a gun that could do it all. In my foolish ignorance, I studied ballistics charts to see what was available and what bullet weights they could shoot. I decided upon the .30-06, because I saw "50gr accelerator (saboted)" loads on the chart (I have yet to see such a load available, and I had to search extensively to find saboted .224 bullets for sale online), all the way up to 220 grain pills. I thought, "this one rifle can be used for everything from squirrels to moose!" Well, that might be true, but I have never been on a moose hunt. Not that I never will, but it's far better to buy a rifle that is WELL suited to what you want to do year in year out. I still own that rifle. It's a Ruger M77 MkII, and it has never shot better than 1.5 MOA, even with handloads and an aftermarket trigger. I picked it because I read somewhere that it was more accurate out of the box than anything else. Lessons learned. I have this strong desire to rebarrel and restock it to try to get it to shoot better, but every time I start adding up the $$$, I realize that it would be far cheaper to buy a Tikka and KNOW that it was going to shoot, right out of the box.
So, your stated goals are to hunt deer and coyote, and shoot matches to 800 yards. Like NBK said, you don't need a barrel burner to do those. But if you want to WIN matches, I think you're going to have make it the #1 priority, because your competition have already made that their priority. Beating them with a "do-it-all" rifle is going to be tough. Of course, that's just a guess, because I've never even been to a long range match, and know nothing about them. But it stands to reason.