Why don't more manufacturers, or even more accurately, why doesn't the general public demand more information on boat performance?
Most people don't care much about this as said previously, so the manufacturers generally don't have the numbers.
Since my current boat is rather slow, I've been shopping for a much faster boat. However determining speed performance has been nearly impossible. About the only rating common to most boats for comparison purposes has been PHRF, which seams to give some indication of performance but not much. SA/D doesn't seam to tell you much, as my current boat has a pretty good SA/D ratio, but is still pretty slow, even in light winds.
SA/D is just one of many factors that goes into determining how fast a boat is. If two boats have the exact same SA/D but one is a longer, more modern design with a high-aspect bulb keel and high-aspect mast and sail plan, and the other is a shorter, full keel with gaff rig, the first is going to be a lot fast that the second because it will have a longer waterline, less underwater drag, and a more efficient sail plan.
A comment made to me by the manufacturer's rep concerning the Hunter Edge was that anything under 20 feet with a keel will be slow, however from what little bit I have seen, the Edge seams like it would be slow as well, even though it is a pretty long boat. But its difficult to know for sure. Why can't one find polars, or even some indication in the boat reviews, some sort of indication like on a beam reach, with ~10 knots of wind, the boat was moving X knots. Then what angle at a close reach does the speed really start to fall off. But no one ever seams to want to publish that. Beneteau seems to be about the only company that publishes polars, which seems very useful for shopping.
Manufacturers often don't generate polars. Also, polars are a bit subjective. If you have a lousy sailor, the polars generated by the boat will be quite different that those by an excellent sailor. There are a lot of variables in how fast you can get a sailboat to move, beyond its design. The skill and quality of the captain and crew matter a lot, unlike on power boats. So does the maintenance of the hull cleanliness, etc.
Last question, can one sail a water ballasted boat with no ballast in light winds? In other words, if the wind is under 10mph, or maybe even 8 mph, can one just leave the ballast out, and make the boat perform much better, or even partial ballast? In theory, an adjustable ballast would be very desirable if it worked.
No, you really don't want to do that. There are serious risks involved and there's also a good chance that your insurance won't cover you if you capsize the boat and damage it with empty or partially empty water ballast tanks.
( I started looking at tirmorans, but they are all way out of my budget league)
Too bad, they're great boats, but my opinion might be a bit biased.