An update:
The Karp's Sweet in southern California did finally produce one big fruit. Unfortunately some animal (either a possum or racoon) made several bite marks into it and deep scratches. Despite this, I did pick the fruit and get an opportunity to taste it. I think it would likely have been able to ripen a little more if it had been left on the tree longer, but with the damage I do not think the fruit would have lasted longer.
It was a huge fruit, much bigger than any apple. (Maybe even a little bigger than a typical grapefruit bought from the supermarket)
The taste, as best as I could tell, was similar to the Crimea. A little dense but kind of edible, but a little too acidic to really fully enjoy eating very much of. Maybe I would say it might just have been the tiniest bit more mild in flavor than the Crimea I tasted, but still "as good".
The next year after that the tree also produced a big beautiful yellow fruit, but an animal apparently took it and it disappeared. (Perhaps this should be taken as a good indicator, since I do not think an animal would have taken a regular quince)
I can't say for sure whether the fruits on the tree are growing so big due to the variety, or the warm climate with a long growing season.
The tree is growing in almost solid limestone soil.
Overall I would say this is a fruit regular people could enjoy if cut very thin and served with some savory dipping sauce (which is the traditional way this fruit is enjoyed in some parts of Latin America).
It might not be something most people would get extremely excited about, but it has a different enough sort of flavor that it could be worth growing, especially for those who like to grow unusual and exotic fruit.
I did cut the Crimea up, boiled the pieces in water for 5 minutes, then seared the pieces in a pan with butter and honey and served them to a 7 year old boy who apparently enjoyed the snack and said they were good, without being asked. This was when the fruit was still smaller sized and less ripe.
I also did find a very large Aromatnaya quince at a Persian market. The fruit was huge and better quality than an ordinary quince, to the point that I could almost eat it raw. I even handed a thin raw slice to a family member who normally does not have much enthusiasm for quince or trying things like that, but even she said she considered it edible and "almost like apple". (It still, I would say, was not quite up to the level of edibility raw as the other special quinces described above but it was close) It ended up being baked into a delicious dessert with pears, to the point that one could almost not tell at all which pieces of baked fruit were pear and which were quince, the flavors all melded together. (I did boil the quince pieces in water for 7 minutes before they went into the dessert to bake, to be sure they would be fully cooked and end up a similar consistency and texture as the pears)
The Aromatnaya might have a little less intense flavor and aroma than other normal varieties of quince, but despite that I would say it is a very good quality variety, and much more on the side of being "edible", if not cooked, or especially if not cooked very long. For cooking in a dessert, I would say that the Aromatnaya may be preferable to the Karp's Sweet, since it is a little more "substantive", might have just a little more flavor, but the Karp's Sweet may be a little better for eating raw, almost "crispy" (for a quince) and "refreshing".
I would not say they were extremely so much different from each other, however. What I mean is that if you have tried a fully ripe Aromatnaya, cut it into thin slices, and you cannot imagine it to be "edible" or do not think it is good, then you are not going to like Karp's Sweet either.
The Karp's Sweet that I tasted (which again, could have been a little more ripe) I really could have imagined to be like a less ripe Granny Smith Apple, except with more acidity (maybe just the tiniest bit mouth-puckering), and a little quince aroma.
