The leetgren bren is worse than the regular bren (never got the 1+ damage) and it is still better at all rangers than the G43. It's about 1.10x better at long range, 1.4x better at medium and some 2x better at short, this is from memory thou.
If you give it the +1 damage the brit bren got, it'd be something more like 1.5x and 2.5xish. If you want to get technical about it, it's a better upgrade than the LMG for regular grens due to the fact that you get 4 of them.
Also if anyone is wondering what the best LMG in the game is, DPS wise it's the support gren MG34, it's roughly got the firepower of two brens and with supression values on top of that