o boy did you ask in the right place
ground cherries:
I love them, but I wouldn't call them a good substitute for a cherry, they're very different beasts.
I'm enamored enough with the whole genus Physalis that I'm collecting species and attempting interspecific crosses with them. at present I've got the annual 'husk tomato', P. pruinosa; the one you mention 'cape gooseberry'/'golden berry'/'incaberry', P. peruviana, which is a tender perennial and dies completely in at least zone 7; the native-to-my-area hardy perennial clammy ground cherry; a couple other perennial ones, species unknown; and of course the tomatillo, P. philadephica/ixocarpa (yup - same genus). then also some potential crosses, too young to know.
no, they're not related to true gooseberries.
the pruinosa has a sweet butterscotchy/pineapple taste when dead-ripe...really nice dried, too, like a good raisin with crispy bits from all the little seeds. I've seen them used in baking, but they get kind of insipid that way, and are much better fresh. if not picked (read: picked off the ground, as that's where they go when they get ripe) religiously they can have a tendency to self-seed and show up the following year in inconvenient places where they for some reason always grow bigger and healthier and more productive than any intentionally planted ones.
the cape gooseberry has more of a citrusy sour-and-sweet thing with a hint of maybe coconut. since the cape gooseberry takes a bit of time to get going I tend to keep them potted in their first year, protect them through the winter (basement when below freezing), and plant them out when they take off their second spring. much better results that way.
the clammy ground cherry has a kind of vaguely tropical sweet apple taste. a handful of these three tastes like a pina colata.
here's a pic of some of each of those three's fruit (clockwise from top left; husk tomato, cape gooseberry, clammy ground cherry):
and an experimental yacon/husk tomato polyculture I tried last year (flowering sunchokes in the background aren't in the same bed):
not that it matters much to the casual consider-er , but the cape gooseberry is a tetraploid, and as far as I know, most if not all of the other species (of which there are quite a few) are diploid. so cape gooseberry
shouldn't cross easily with the others, but there may be real possibility of crosses between the others, most of which are geographically distinct in the wild.
I guess that's enough for now...