It is compact and light weight. It comes with it's own stuff sack. I use a waterproof bag for it as well. It fits nicely into my kayak. It comes with a ground cloth. And it is available in white - any other color will not be as breathable and waterproof. Thus far, that has not been any problem for me. And the trade-off for some "cool" color is well worth it.
I'm 6-3 and 245 and haven't fit any other bivy sack - the Uber Bivy is like the Taj Mahal. Lots of room, a couple of convenient pockets for glasses, wallet and such. Set up is a snap - two identical, flexible poles slide into the bivy and form a space for your head. A mosquito net or a solid closure allow for a comfortable night either under the stars [and bug free] or snug in your own world. Both work well.
Dave Miles knows what he is about and makes every bivy himself. He only sells on the internet and by word-of-mouth. Just Google - Miles Uber Bivy and/or go to milesgear.com
I have been out on one of the largest lakes in the country in 25+ mph winds and seas about 2-4 feet. Also routinely paddle in a smaller lake with winds up to 40 mph and waves to 2+ feet. I've never felt uncomfortable in any weather. This boat loves the rough water - coming from any quarter it is predictable and very well behaved. If you have any issues, drop the skeg and it tracks like it is on rails! Half skeg with a following sea will usually set you up well.
The Nighthawk is very stable and even more so with a load. Pick up the skeg and she turns very well, indeed, taking an edge nicely and coming around in a very fast, secure manner.
The hull is tough, very tough. I have put a couple of pretty good dings and they are easily repaired. All the pertinent info is on the Eddyline website. If you have any problems, call them - they are all about helping their owners!
I'm 6-3 and weigh about 245 with a 32" inseam - a long torso with a high CG. The fit is awesome.
Nighthawk will pack a ton of stuff - way more than you should take - I camp with a lot of luxuries [a chair, table and thick sleeping pad] as well as the usual cooking implements, sleeping bag, food, and clothes. And I still have room to spare. While loaded she moves well - a couple of strokes and it is up to speed.
This is a terrific boat! If you can find one, get it!!