Let me answer directly to you. I am developer/productmanager of the hammocks and other products like the mats at Exped.
Concerning the length of the Ergo Hammock, actually the new 2013 version which comes out in march is 25 cm longer so also longer people respectively the ones sleeping on their backs can use it. Concerning the 2012 version, consider that the length of the mat is not automatically the length of the person, because 70% are sleeping on their sides which always is kind of a phoetus position hence you are quite some smaller than the body length indicates. So we found it would fit many poeple, also 180 cm long ones, but best is always to try out than just looking a the figures.
Concerning the fabric which slightly opens its structure at the stressed seams: With any lightweight fabric this phenomenon happens: the threadsd, mainly the weft threads (sideways threads) will shift slightly giving the impression that the fabric might break because you see light through it. However there is not any breakage of threads whatsover, it is just the thread structure which shifts and slightly distorts. Again that is the price of real lightweight fabric. You will find this on any hammock with lightweight fabric on the market along the stitch lines where stress is exerted. I have made alot of tests accordingly, also with existing competitors hammocks. You might check out any hammock accordingly with a magnifying glass. After a certain while again it happens with all lightweight fabric because less the number of threads are diminished. It is important to know that it is not a good option to diminish the Denier count (weight of threads per 9000 meter) to have more threads because of strength issues. When we do that like in the Scout Hammock Combi where we use 20 Denier instead of 40 Denier, we take the fabric double.
Again this is by no means a strength problem, it is purely esthetical, but I think acceptable given the fact that as light as possible fabric is used as I assume a certain understanding can be accepted by lightweight minded hangers. In the new 2013 version you hardly will find this issue because we have a way to hide it, but hey, as explained, it is still there because it is unavoidable with any stressed seam on lightweight fabrics,
mit bestem Gruss / with best regards,