I have a Super C barley, perfect for my commute, change of clothes, plus tubes / tools / mini pump and a jacket. Quite a bit of room left over as well.
I started using it without a bagman, and found it too far tilted back when strapped to the seat post (hitting my legs, plus I didn’t trust the outer pockets to be very secure when tilted at 45 degrees) and without strapping it to the seatpost it swayed too much.
So I got a QR bagman without the wire support, mostly for the quick release aspect, and then bent some 5mm steel rod into an appropriate shape to stop it tilting back – the pockets are now back to the horizontal position. I didn’t bother with the bottom support that the proper bagman has cos I think the Barley is small enough that it’s self supporting. It also looks neater when the bag isn’t attached.
Worth nothing that if you buy the bagman QR without the wire support, it’s exactly the same as the wire support version, but without the wire support, sounds obvious, but it has the holes (already threaded) so you can add your own support if you need to later.
I’d post a photo up, but I don’t have one handy, I totally rate the carradice stuff, really like and the super C barley is classic looking without the tedious buckles!