The SuperUniti has not been launched yet, so only a few people - outside Naim - have heard it.
Whether those few people have also compared the SuperUniti to the equipment you mentioned is unlikely. (Possibly just a handful of reviewers who will want to hang onto their findings until publishing date.
The Stream XP is touted by Cyrus as a slightly better pre-amp than the PreXp, so we can safely say that it's better than the pre-amp section in the 8xpD. And obviously, the X Power is a better power amp than the power amp section in the 8Xpd too. So from the Cyrus combos, ifpd go with the Stream XP and X Power. This will widen your possible choice of speakers.
The SuperUniti will be with us in October, so comparisons can be made then