What Lady said... literally no point for Bren when you can get DPs in many other docs. Also the Thompsons are pretty strong so it's not like the current iteration of Ass Guards feel like they are UP...
it's not a question of UP or OP but versatility. I'm suggesting converting this unit into an all round versatile combat unit like rifleman. Zooks for AT, thompsons for cqc and bren for ong range. And the bren is for lends lease flavor as it's very similar to dp28.