To bad it's not possible.

I've added a Pitbull's focustarget frame to all my clones and adjusted it so it only shows the name in some large font so it's easy to read on all screens.
(Focus is my current main, I'm not sure if it's possible to have a frame just for the party1target, but you could check it on the partytarget's frame aswell,
Party1 is in the same place for all clones anyway)

Works great so far.
I'm thinking about adding a macro with raidmarking,
so it becomes even easier to spot if they already know which target I'm having.
(originally I wanted just a frame to change color if they had the same target, but that would result in the same lag)

The biggest problem with the lag for me would be in PvE raids,
I don't want to mess up a raid by accidentally nuking a sheep or another group.

Offcourse it's annoying in any fight,
but in PvE you have the time to check for it,
I doubt it's usefull in pvp, but who knows