Some of the issues I have are with the design. The cuff adjuster is a single button elasticated tab that when pulled has no further anchor point/button to keep tension. I expect a second button would do the job nicely and pull the cuff in sufficiently for a wearer who had no gloves on, therefore offering some protection from the elements. Otherwise it just forms a useless loop, even though some tension is formed with the material it's not weather tight. Seems a bit daft considering the material and how these materials can beat the elements. However, I've had mine on earlier this evening with some shearling norse p gloves and the cuff works brilliantly when wearing gloves but without it can feel a little open, so with gloves as you would probably wear with a winter jacket the issue becomes redundant. But still, a design point that could be improved.
I know this is an old post (great review btw!) but I thought that I would reply just in case you or someone else is still finding the sleeve openings to be too wide. My friend just demonstrated to me how you can also use the cuff adjuster to make the cuff tight. You will first need to pull a bit of the elasticated tab out and then just roll it the other way around the sleeve and then button it. It should then tighten the cuff around your wrist. At least in a new Ten C Parka it really hugs your wrist if you do it like this.
I took a pic to show what I mean (as I probably didn't manage to explain it as clearly as I wanted):