I picked up my Mt. Washington when I went to visit the Burgeon showroom after Christmas. I've had it about a month now and I've worn it for just about every hike since the new year, so I'd say it has about 100 miles of trail time now. First the fit, I agree that a cinch at the waist would be a nice addition but, the waist belt on my backpack does a perfectly fine job sealing my top. Other than that, the fit is very comfortable, I wear a medium, and there is room for an additional layer of insulation though I only run a base layer and the Mt. Washington for my kit.
Insulation: There have been a lot of really cold days this month, the most extreme was -17f at the trailhead. I wore a base layer and this jacket and was perfectly warm with no issues or concerns, there was no wind but it was the perfect protective layer for the day. The Mt. Washington insulated even when I started to sweat through and the jacket was damp. the fitted hood is an excellent sealing layer around my head over a balaclava or even just a neck gaiter. I have noticed that wind can seep in through the zippers and I have felt that cold seepage on the arm zippers mostly.
Wind and water resistance: I haven't really tested this yet, I'm planning to get up Mt Monadnock or some other bald summit in a storm to give the jacket a good test, if I remember I'll make a video and share that.
Overall: This is a great multi-use jacket that keeps me warm and has taken the worst of everything I throw at it. The zippers all work, even with gloves on and they are roomy enough to access with gloves on as well. My only complaints would be, I'd like the front pockets higher to fit around a waist strap on a backpack. I'd like to see the cinch on the bottom for that added level of control when buttoning up the system. And lastly, I want a hardshell... Burgeon, please make a hardshell!