Welll -- I also have 2 BARs, but only 1 Bren (for that matter I have 2 Thompsons and 3 Stens - what ever that is worth?)
The Bren is so much more fun that I rarely shoot the BARs. I also shoot the Bren with the carrying handle opened out and the butt tucked agains my side for "assault" fire. I disagree with those who say this doesn't work for whatever reasons stated! I have shot a variety of targets - sillouetts, bowling pins, usv from both standing and walking positions. I find the Bren to be quite accurate in this mode! Of course I do not fire long bursts - Not good practice with ant FA! 3 to 5 rds at a squeze is my normal, but often repeated immediately.
I find the weapon to be both accurate AND a pleasure to shoot in this mode!
By comparison the Only way to shoot the BAR comfortably is from the prone position with the bipod.
Lets drop another weapon into the discussion - The MG 42. I find it not uncomfortable to shoot mine from the "assault" position - sling over neck, holding the bipod legs in my left hand AND shooting short 5 - 7 rd bursts. Anything longer and it quickly gets away from the target area.
The Bren is the most enjoyable to shoot in this mode because it is a good bit lighter and the slower rate of fire makes it more accurate. The BAR is the worst, even with the bipod removed to lighten it up.
Sarge