I shoot 308 my brother shoots 6.5 creedmoor on my 500 yard range. He is shooting 140s just under 2,700 ft per second. I'm shooting 165's at 2800 ft per second. Slightly longer barrel. It's rarely windy where I live and my range is a 150 ft strip with tall timber on either side. He runs a can, and I Rock the world.
We shoot each other's guns all the time.
Here's my take having shot them both side by side in nearly identical rifles.
At 400 yd our rifles throw equal trajectories and in fact I think mine has a one half inch edge. At 500 yd you can just barely begin to see the 6.5 pull ahead.
The 308 burns more powder, throws more lead, and kicks harder. The 6.5 is more fun to shoot. You can still botch it up, but with a good trigger (and reasonable rifle weight) it's easier to shoot well. When it comes to making shots that anchor deer immediately, the 308 at these ranges has a slight advantage using an optimal bullet. Especially if shot presentation isn't great, and you have to take it anyway. Both cartridges are perfectly adequate. It's funny how hitting the right spot is more important. Energy is not everything, but it certainly isn't irrelevant either.
A 6.5 Grendel doesn't equal a 6.5 CM.
If the grendels get mad so be it.
A 6.5 creedmoor doesn't equal a 308 below 400.
If the creedmors get mad so be it.
A 308 doesn't equal a good hand loaded 30-06
If the 308 guys get mad, so be it.
You're close. Shoot what you love and shoot well.