Looking good Scott! Mine are getting better too. I have to divide some next year to fill in a few gaps but they've done well considering I've neglected them since I planted them.
Looks like next year is year 3 for all of us. Hopefully we'll be posting walls by then. Some of my 6 plus year olds are 5-6 foot in diameter. These screens only have one way to go. Unless like me, you do everything possible to kill them.
Thought you might enjoy viewing some mature plants. First photo shows Miscanthus Gracillimus that makes a decent screen although not as dense as MG; you can often find Misc. Grac on sale as field clumps for 2/3 bucks. Second photo shows 3 Mis Gigan plants that provide almost 14' of screen. 3rd photo shows 5 misc gigan plants that make over 25' of screen. The photos you have posted show fairly dense planting; you will be able to eventually transplant every other plant as field clumps (break each plant into 3-4 clumps. Last photo exhibits a misc gigan field clump that was planted in July. One additional tip for those planting double rows; if/when you cut back your plants in the spring, place the cuttings between the row s as mulch ... it works very well.
Here are 7 1-yr old porcupine and gracillimus miscanthus plants that will provide a screen between a Norway Spruce and a 59" 1-yr old direct seeded Dunstan chestnut tree
A couple of them are a little ragged because some cattle got out of an adjoining pasture and walked/stomped on a couple of them; however, once established, they are very hearty and drought resistant.
I encourage you to mulch if you don't already do so .... it's my experience that miscanthus doesn't tolerate competition very well ... especially grass. You might try a strip of 4-5 plants and see what effects are achieved; a little test to determine if it is worth mulching. Good luck!