A center oneway allows for the front belt layshaft pulley and everything forward of that to freespin (oneway) off throttle. So in a sense it wouldn't make much of a difference with a front oneway too, but you could run a spool in the front and have locked front wheels that freespin off throttle or a diff in the front for a oneway differential action. But I've never seen any car run better with it which is why we've never developed one, like Jon said it isn't necessary.
Schue white springs (14lb) all the way around seem to work great on tons of surfaces, I've run that on indoor asphalt, outdoor asphalt, and carpet with rubber tires. I put a schue blue (16lb) on the front of my car right now because on a tight carpet track the whites were too lazy and not responsive enough. I always run a lighter oil on rubber tires (25-35wt) with generally a 5wt split, running a thinner front oil. Right now I'm running 25wt front and 30wt rear because it made the car much more responsive. And btw Jon the green spring is rated at 18lbs