1) Having the ability to quickly load and unload the backstay (and therefore the forestay) is a good thing for all sailing, and has nothing to do with "racing" per se. But you know that. It does have a lot to do with sailing to windward.
2) Navtec adjusters may or may not be in production any more. I thought that after Lewmar bought them, they later discontinued them, but am not sure.
3) EY installed them on their 80's boats, along with the Olsons.
4) After having our original Navtec unit rebuilt once, and having it again fail to hold pressure a few years later, we replaced it with a "SailTec" unit. Still working fine.
5) A friend of mine with an E-32-3, replaced his with a winch-handle-operated mechanical adjuster. Might have been from Wichard. Not fast to adjust, but it works and is 'simlple' in concept.
Edit: I wonder if a failure to hold pressure might be remedied for your brand as it was one time for ours?
After a season of having our Sail Tec integral adjuster "go slack" after aywhere from 2 hours to a day or so, I called the company at the end of November. I spoke to Bob, who seemed very knowledgeable and might be one of the principals. URL...
ericsonyachts.org