Information comes from reviewers (such as Pez, Cycling News) even though most reviews (in the same group) don't test gigantex rims nor open mold ones, and the magazines which, again, don't test the open-mold rims, and of course the marketing departments/persons of ZIPP, Hed, Bontrager, Enve, and so on.
This is in no way stating that the reviews of professionals such as Pez or Cycling News, nor the magazines, do a bad job with reviews. They perform excellent reviews, are professional, and have a mostly* trustworthy voice on issues. What is being pointed out, however, is that they do not test the open-mold products.
In the last 25 years or so I've read plenty of reviews that read like ad copy because they are. Look at reviews vs ad space and get back to me.
Regarding reviews on open mold products I read two just recently but the products weren't identified as open mold products since they had been branded. It happens all the time. That's right, all the time you just don't know it.
Another point, pretty much ALL factories offer open mold products regardless if they are rims, pumps lights, frames, bars or anything else you can name. It's just how it works. These same factories also produce proprietary goods. The fact that they offer open mold products is not a reflection on their quality or capability; It's par for the course.
As to R&D, ALL rims are built and tested to EN standards and yes, Gigantex and other reputable carbon vendors test their rims (unlike most Chinese consumer direct vendors dumping their products on eBay or Alibaba) because of PRODUCT LIABILITY.
For hubs I'd give the nod to the CK hubs. The Zipp hubs do not have the best reputation whereas the CK hubs are stellar. Suggesting that both hubs are the same because they are made from alloy is like saying all violins are the same because they are all made from trees.
We just spent the better part of a year developing hubs for an OE customer and believe me, there is a lot more involved in the design of GOOD hubs that meets the eye. Things like material and hardening choices, bearing placement, flange diameters and decisions about bearing bores, the ability to preload or not, design considerations that affect serviceability, and WEIGHT just to name a few.
Has Zipp been a market leader in terms developing new shapes etc? Yes. They have also been a leader in terms of marketing. Their in-house testing is skewed heavily in their favour while independent third party testing tends to close the gap quite a bit with Zipp still doing very well. They clearly are very good rim designs.
Specifically to the OP, one concern is spoke count. For your weight 16/20 is pretty low, 20/24 might serve you better.
On paper the Zipp wheels may be the better product but are they better by 200£-300£? And are they the best choice to meet YOUR needs. I'm not as sure as others who seem heavily influenced by brand and marketing. Either way you'll end up with quality wheels I'm sure you'll enjoy.