6.5-284 is not a great choice unless you're made of money. It's a barrel burner.
Speaking of barrel life, .308 is going to be at least double that of 6.5CM. Maybe closer to triple. Figure 2,000+ for 6.5 and lots more for .308. Those are VERY approximate numbers.
When you figure a barrel will cost you $600 to purchase and install, it's a very significant factor in real world cost per shot.
To me, the ballistic advantages of the 6.5 outweigh all the pros of a .308. For my money, I'd buy a 6.5, shoot the crap out of it, and then decide if you really need or want a .308. For me the answer was, and still is, "no".