I switched from .308 to 6.5 Creedmoor and had some of the same concerns. I switched last summer and haven't been able to find another box of 6.5, BUT I almost never go looking for ammo, and all the times I did look, I couldn't find .308, .300blk, .223, or .22 either, so my experience doesn't tell you much. The suppressed 6.5 Creedmoor is much more more pleasant to shoot than my unsuppressed .308 with a heavy wood stock, but no muzzle device of any kind. I've shot both only out to 400 yards with equal ease, and missed animals at closer ranges with both. Many comments made online make me question the ability of the 6.5 to put down an elk, but then friends with way more experience and understanding of ballistics tell me I shouldn't be worried at all.

That probably wasn't that helpful except to let you know that I was basically in the same boat but made the switch anyway.
The deciding factors for me were:
- that I have the ability to shoot longer distances if I ever want to and figured that the 6.5 would do that better.
- I bought a can to put onto my .308 and found out it would cost me the cost of my rifle to get it threaded.
- I wanted a cool new gun and could afford it at the time.