I have tons of miscanthus and moving it in the fall is a bit risky if it bloomed. At the time of bloom (mine bloom from July through October it is at its weakest because it has expended all of its energy). It would be best to wait until spring.
If they have not bloomed then it should be fine. You can transplant as many as you like. Just make sure you take a nice clump of soil with them, get them into the ground quickly, water them (no fertilizer, but compost is nice) and they should be perfectly happy.
I apologize. I should have asked whether they had bloomed.