Unfortunately, they do tend to be a little bit of trial and error. This holds true even within a brand and model. "Fair-trade" hammocks are both the best and worst way to purchase a hammock. For all the moral reasons, they are great! You also stand an excellent chance of having a very fine hand-made hammock that will provide years of comfort. The other side of the coin is, these are generally hand-made hammocks; expect subtle differences based on the hands that are making it. By and large, the odds are in your favor. I'd be remiss if I didn't bring up the possibility of a bad hammock; it happens.
With that out of the way, IMO, you are looking in the right direction. Size does matter to me with my indoor hammocks. Bed length is important, but overall length is also very important. I try to keep them all at least 12' long overall. My favorites tend to be closer to the 14' mark, but some of the shorter ones are quite comfortable. Again here, playing the odds as I fell more likely to gain comfort from overall length.
The hammock you listed has an overall of almost 14' and a bed length of 7.5'. These are both very good indicators in my mind that it will be a comfortable hammock. It is generously wide, which means you can get as diagonal as you would want...another good thing. It is on the pricey side at almost $200, but that is also usually a good indicator to the quality. Not always, but usually. This at least implies that they are using a quality cotton sheet that will likely be thick enough to provide some degree of warmth and longevity.
I could live without the orange color, but.....
I say go for it and let us know. At less than $200, it's still a whole lot cheaper than even a cheap low quality mattress set.