BPL member BillyGoat (aka VirgaOutdoors) made me a new SUL quilt that I'm pretty stoked about. He's calling this quilt the Wendego. Mine is all M55 and uses 7.6oz of 900fp down, 0.51oz cuben baffles (19 of 'em).
I'm really happy with M55. The stuff seems totally downproof....I've used this quilt for several nights and I haven't been able to find a single bit of down popping out. With reasonable care, I have no durability concerns with M55 as a sleeping bag shell fabric. It's a bit slower to loft up than some other shell fabrics because the air permeability is sorta low, which comes hand in hand with it's great down-proof-ness.
BillyGoat is rating this quilt at 35-40F, which makes sense since it uses 7.6oz of 900fp down. That's 0.5oz more than Katabatic's 40F rated Chisos quilt and even 0.3oz more than Zpacks 30F rated quilt/bag (Zpacks uses 5.5oz in their 40F one), so this quilt should actually be warmer than all of those.
I think this quilt is an nice alternative to the Chisos at a similar price. You save a couple ounces using the lighter shell fabric, which is then spent getting a bit wider cut and more down. Like the Chisos, this quilt is 52" wide at the shoulders, but it's stays wider so you have a lot more than 42" at the hips which is nice.
The quilt as delivered weighed 14.6oz on my scale and it now weighs 14.3oz because I swapped out the cord and cord locks for some lighter stuff.