The healing is very nice to have to bring back overcharged plasmagunners (or meltagunners if you use them and they are killed). Also it might just give an important character one more round on the table now and then.
I tend to run them as suicide plasma squads
an advantage here is, that due to their small squad size you can squeeze 3 squads in a single Valkyrie or Chimera
And a last (if again very situational) possible use: if you for some reason want to run melee guardsmen (regardless of Bullgryns and other more effecient imperial options) they are the only infantry unit that can take pure Laspistol + Chainsword. Three Catachan Command Squads + Straken + Ministorum priest therefore bring 12 x 4 = 48 S4
CC attacks (+ those of Straken and the priest). And if you order them to fix bayonets that rises to 96 attacks. I seriously have no idea if that is worth it (I suspect no from a strictly competetive point of view), but if you want to try something new, why not.