Pretty much everyone gives them something worthwhile. Makeda and Xerxis can give them better defense, Rasheth can stop berserk with Carnivore, Death March from Hexeris gives them better
MAT and Vengeance, Zaal's feat just makes them sick... The list goes on.
As for dealing with them killing each other, it's really a matter of practice. After playing eButch doomie spam without
UAs for a couple months, keeping models from slaughtering each other isn't really an issue for me anymore.
Personally, I'd probably take them over Praetorians. The higher PnS and reach are wonderful, and Berserk will let them kill as many (if not more) targets than Praetorians w/
UA. I'll basically be treating them as Doom Reavers, as while they lack Weapon Master, the ability to target them with spells makes up for it
IMO.