Both of the grasses you mention should do fine in 5 hours of sun. 'Karl' is especially shade tolerant, but 'Hameln' should also work. I don't know what zone you're in, but my 'Hameln' are just starting to bloom now.

Check the list of shade tolerant grasses at bluestem.ca, linked below.

Here is a link that might be useful: Shade Tolerant Grasses

Karl was in a place where he received less than 5 hours...just under the overhang of the house. The one seedhead was at the edge of the plant where it received just a little more sun. I moved him today, where he's out from the shaded spot and will definitely receive 5 or so hours from here on out. Hopefully next year he'll have a ton of seedheads.
Bought a Korean Feather grass for the spot where Karl was, hopefully it will like it there more.

My Hameln haven't bloomed yet. I'm zone 6a, so maybe it's just going to take a bit longer. I just planted them this spring, though, so maybe I will have to wait until next year...