Edible cacti in USDA-Zone 6b?

I recently found a supplier for cold-hardy succulents who has quite a collection of cacti that should even work here in USDA-Zone 6b. Most of them are Opuntia sp. and Echinocereus sp. and some of them have edible fruit. I was interested if anyone here has tried these species in such a cold climate and could give me informations about the quality of the fruit and if they even give mentionable yields.

The ones I'm interested in particular are E. engelmannii, E. fendleri, O. phaeacantha, O. engelmannii and O. macrocentra, but of course I would appreciate informations about other species as well.

Thanks in advance,
Florian