Ok, I don't really know how many of these things are uncommon, but it's mostly just some things I've noticed as being kinda rare in porn.

CV to AV/UB/etc. This is something I've only seen a few times sadly. Most of the time CV just ends in cum digestion with the fur that did the voring then just pawing off(or sucking themselves off).

TFTG with a female being turned male. Another really rare one. I guess part of it is that there are a lot of males in the furry world, so males being turned female is a lot more common(and other reasons, of course). Just seems a shame not to have things happening the other way around.

Dominate mpreg. Ok, what I mean by this is the person getting mpregged being the dominate party. Seen plenty of mpreg with the one getting knocked up being dominated, just would be cool to see it happen the other way around, with the one getting knocked up dominating the other.

Speaking of mpreg... AV to mpreg is something I don't think I've ever really seen either.

There's probably a lot of other things really, but those were just ones that'd popped into my head.

Also, randomly, does anyone know someone who does good dinos(feathery ones specifically) and vore?