Ron from mountainlaureldesigns.com here.
Looks like some good work on your part.
Here is some general info on Spinnaker fabrics gleened from extensive testing I have done on at least 20 samples from various makers / sources.
Spinnaker mfgs use sail makers yards 28.5 X 36(sm/yd) vs. the more common square yard 36 X36 (sq/yd) , in listing weights. Sometimes the weight is the uncoated weights or even the model number and not the weight at all.
Using the Kite site .5 you mentioned as an example:
.5 as the sm/yd in uncoated
times about 1.26 to get sq/yds = .63
and then the rest to get to the 1oz sq/yd is the coating would be my guess. BUt then the coating would be bomber so my guess is that the .5 is off to start with as the mgr's faulty marketing buzz.
Coating types also play a big part in the spinn fabric just as in other nylon fabric coating.
We are all most familiar with PU and Silicone coatings and Spinnaker fabrics use those plus a whole lot of others.
SO, in looking at any spinnaker fabric products, compare the final weights of the items and don't look too close at the number in the name or raw fabric weights unless it is stated very clearly that the fabic weight is for fully coated and in sq/yd for apple to apple comparisions. Even then the coating type and application process can make a big difference in water resistance and strength.
I tested many spin fabrics that were very very light and strong enough but not waterproof enough. I ended up settling on the .97 Spinntex Pro as the lightest fully waterproof in all rain conditions when used as a tarp. It is silicone impregnated and the .97 sq/yd is a finished and coated weight.
To be fair, I can say that in my opinion the gossamer gear spinn fabric used in the spinnshelter and spinntwin (as well as the BPL PRO fabric is fully waterproof in all rain conditions
The Spinntex Pro .97 that I use is avialble by the yd from thru-hiker.com in smoke gray and is the only non white avialble in that light weight and water resistance I have found.
FYI: I did test some of the kite site's .5 and .7 but found it's coating to be too thin to stop even med rain. The current stuff on sale may be different from waht I tested... Just test it well before doing all the work sewing.