The WCR is a lot more rolly (mostly because of the core shape, I believe) and handles slightly more oil because of that, as near as I can tell. If you really want to handle thelighter side of medium, I'd go with the BRB, as it normally gets lots of length, as well as a sharper backend.
I'd be inclined to suggest the BRB with around a 5" pin to PAP (for 300 frpm rate or higher) and placing the pin over the area of the bridge. It shoudl still tickle that medium oil range, but be much better for lighter than mediums than the WCR.
Neither has much flare so be careful about using too long a pin to PAP.
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