Hello very interessting,
i test the same situation too. I have some Nikon SB600 Speedlights and a Phase One Camera.
1) I bought the cactus V6 II. HHS and manual flash override should work. But it does not! I have some mails with cactus support and the say the MKII does not work with phase one. -> goes back to dealer
2) I bought the cactus V6: No HHS is working on this version. power override to the SB600 work. But connecting the SB600 with the trigger you can do nothing any more. No zoom control nothing on the SB600.-> goes back to dealer
3) i bought younguo YN622 and TX. Nothing worked! No power control to SB600 or Sb900. Sync worked not all the time. -> goes back to dealer
4) I bought now the YN560 mark III and 560 TX. And it works now. Not with HSS of course...
only my experience..