Will post soon on how they look and how they hold up in washes. Its easy to install and remove in any case. Many "common man" shirts over the years have used collar stays of plastic or metal. To me this is not much different solution.There are numerous video reviews. Its literally a plastic stick sewn between the placket layers. They look ridiculous, and I can't imagine they do anything good for your garment's longevity.
I dont buy linen shirts, but I did just buy another pair of the non iron shirts from Proper Cloth with the standup placket to see how this looks. There will be no smooth vs rumple issue in this case.I have the PC 'stand up placket' on a linen shirt. It works fairly well. The downside is that it's just a fused placket with medium interlining, so the placket is always completely flat and smooth while the rest of the shirt is rumply as linen usually is. Overall, it's better than not having it
The best solution th this problem? For dress shirts or thinner fabrics in general, I find that a bit good old fashioned spray starch works wonders.
The best solution you suggest is not really the best solution for the PC shirts I buy, which are all non iron, and most are non iron + stretch. This type of shirt works best for my lifestyle.