The people who bought them are clearly happy enough not to have complaints. There are some that would not buy sails like that. The difference lies in the level of expectations. Top level racers will probably never purchase anything other than "racing sails", from the few vendors who are currently competitive in that market. People who go by price will probably not look at anything other than the cheapest option. Nobody goes out and buys two sets just to compare them (and few enough have the opportunity to sail on or compare many different boats).
I'm perfectly happy with the sails I bought from
Hank Jotz. He makes them in some Northern California wilderness, so you have to snail-mail your order with your check so he can pick them up when he gets to the general store for his mail delivery. He'll call you and discuss your needs / style of sailing / details of your boat, etc. before he starts the work or cashes your check. The level of craftsmanship is excellent, he has decades of experience, supports the DaySailer Association by advertising in the Day Sailer Quarterly. The price is in the medium range between the cheapest and the most expensive sails you can get for a DaySailer.
I'm not a sailmaker, so even if I were to look at the sails I got and some other ones, I would not be able to give an expert's explanation of any design differences, but I suspect some positive correlation between quality and price. How would some tester rate them? Who knows? Does the range go from "fair" "good" to "very good" or from "good" "very good" to "excellent"? I suspect nobody here really has a definite answer. I think the sails Alan has are probably "good" (or better) whereas the ones I have might be in the "very good" range (hopefully the ones sold at a premium as "racing sails" are really "excellent"). The reason for thinking that is because he and a few others are really happy with those sails, and that argues against them being merely "fair". (And I for sure hope that I got "very good"

)
I got about eight seasons or 120 days on the water out of my first set and then the jib showed signs of being tired (leech started to flutter). I retrofitted a leech line, which stopped the flutter at the cost of a tendency for a hooked leech. Many would call the sails still usable for cruising. However, I decided to replace. While I'm not a competitive racer, I do participate in a mixed fleet beer can series and I enjoy sails that set properly.
Because you are questioning, I would recommend that you go with some mid-priced offer, and be sure that you get more than "good" in terms of quality.