Here are some more pics and details.
As far as the button mod, I just used Dritz Snap Fastners
and affixed them to the edge which I re-enforced with bias tape. They work ok, but it's a pain to get everything lined up and securely crimped together. I've already had one come apart on me too.
For anyone wanting to duplicate I'd recommend sew on snaps or just getting a long zipper which is probably cheaper and easier.
Here's the lower part which is one vest with sleeves removed (still need to figure out how to close the arm holes when in quilt mode - probably add zippers).
Quilt/Sleeping bag mode. You can put your arms in the - well arms
- which should be nice while reading at night or trying to emulate Shug and making "breakfast from the hammock".
You could also switch which side is the top so the zips are either in front of behind you - since the front of the jacket seems to have more down you might even be able to alter the temp rating somewhat by flipping it over.
Worn as a vest or if it's really cold vest + jacket. Since the extension piece still has it's zipper you can open it up and still easily walk. So if it's really cold in the morning you could just unbutton the middle toss the lower part over you and you're ready to go without having to really get out of your cozy warm down.