Cart bags users - Mizuno BRD4 good? Is waterproof bags needed?

Haven't used this Mizzy bag but, if I'm honest, I probably wouldn't have a cart bag that doesn't have some degree of waterproofing.
Most bags seem to be made of the same material as T bags.
It rains in the UK - mostly when the forecasters say it won't - so I think waterproof is the way to go.
The downside to waterproof bags can be that the pockets seem to be smaller and not necessarily placed where they're most useful..they're placed where they can angle the zip so water runs away from it.
I have the Ping DLX, an older version but it's made of a PVC-like material so most of the rain falls straight off.
1 po ket can get a bit damp but that's the one I keep tees and ball markers in.
The rest of it is pretty sound.
I had a Callaway waterproof bag that was excellent until it wore out.....