I have a three-phase round arm Wadkin BRA. Although I have a rare riving knife (for some reason best known to eBay I bought two of them!). But I have only ever used it for crosscutting, with a negative rake Atkinson Walker blade. I've set it up for a precise 90 degree cut, since that is mostly what I need it for. I recently put 10cm thick oak through it, 40cm cross cut - and it went through it like cutting butter, absolutely no hint of lack of control. It is a hell of a good machine. You need some decent dust extraction though.
Anyone need a Wadkin riving knife? I have a spare one looking for a home.