seeing reports in Doffjobs channel that crossfaction doffs work when bought on the exhange. Is this intended? Not rewards, plain ordinary klingon doffs working for feds after buying them.

Not intended. Thanks for the head's up. I have forwarded this to Software.

I tested this both ways, with a gorn on my fed, and a vulcan on my kdf. It didn't work

I was one of the people to test this a couple hours ago. Directions to reproduce:

Post doff on the exchange

On buyer character, make sure you have a slot open on the active roster
Search by their name under "Any" (there's no doff section in the exchange yet)
Buy
When buying they'll go directly to the active roster. If the active roster is full the purchase will fail (unless they are a doff type that can't be assigned to the active roster, in which case they go to the reserve roster). From there they can be used on the active roster, or removed from it and used on assignments.

I've transferred two doffs this way, a Klingon and a Lethean, and have been using both in assignments as I would any other doff.

The OP said boff not doff. Was that a typo? I didn't know doffs could go on the exchange

It was a typo, meant doffs