I am still happily using mine. I have learned that it is critical to have a perfect seal or its near useless. I highly recommend adding draft collars at the head and foot. I've also tweaked my suspension a few times to help with the seal. My latest suspension setup uses shockcord along the sides very much like the Knotty hammock Stretch side mod. I also have shock cord in my draft collars to help pull them into the hammock tight. The end result is a perfect seal. I can even go fetal position and it conforms and stays sealed.
I've had my UQ down to single digit temps and been OK (this was before my latest suspending trick so I expect to be a little more comfy next time). For cold camping, I now also bring a light / cheap truck windshield protector and lay that between the hammock and UQ. Works a treat. I just got back, from a campout last weekend where it was 24*F and I was warm.
As disclaimer, I do use 2 16oz hot water bottles and bundle up.