I've got a new 2016 MBP and LG UltraFine 5k on order, and I'm looking at some decent desk mounted monitor arms for the 5k. I've got a single 5k for now, and I'll pick up a second one before the sale ends if it works out. Ideally after a dual monitor arm or two single monitor arms that will bolt to the desk rather than clamp. I saw some Humanscale M8 arms in the owners thread that look great, but very pricey. There's also the Ergotron MX mounts, which look like a cheaper version of the M8 - http://www.ergotron.com/en-us/products/product-details/productid/170#/ So if you've mounted them up - what are you using?