Personally I'd say something bigger would be better, but depends on the space you have. I have an L1361, which is the baby of the L series but I love her! Big enough to go anywhere (well anywhere I have tried!) but small enough to move round small areas and some of my gates are only 7 foot and she will fit through them.
The B series I think would stuggle to lift a 300kg bale on the loader, but might do it on the rear linkage. The problem I find is that the implement you need to attach to the loader/rear linkage is often so heavy that it limits what you can lift.
However the L series will be quite a bit more money, I've still not told my wife how much mine cost!

Kubota is the make to go for so you're on the right track!