Dont worry about losing trading post units, they always rotate it every few months with the same units. (at dmm at least)
If nutaku finally starts some kind of rotation, it should be similar to dmm's. And you'll eventually see spica/saki again.
Another noted unit that everyone wants is the plat healer http://millenniumwaraigis.wikia.com/wiki/Chydis
got her on dmm, still waiting FOR THE GODDAM ROTATION on nutaku. ayy lmao.