I've tried many crosses this year (at least around 20) with Hildewintera hybrid "Aurora" as father. No fruits except for what looks to be a small fruit is forming on a chamaecereus hybrid (it's still quite newly pollinated so it can still abort).
Since a hybrid like "Aurora" has echinopsis genes inside it I think it would be possible to use it's pollen for a successful cross with an echinopsis, but no luck so far.
Has anyone experience from crosses like this?