I think that one of the primary problems with the cox reed valve design is the way the reed is returned to closed position. If you think about it, there MUST be a significant degree of reverse flow to return the reed to it`s seat. This means that the standard reed setup "floats" at EVERY rpm, but gets worse as the rpms increase and the reed needs to be moved more quickly, thereby allowing even more blowback.
The Vshaped reed setup gets around this by having reeds that are sprung closed- helping the return (but hurting the opening) process... but seeing as the intake closing time seems to be more critical than the opening time, a gain may be realised. Also the V shaped reed may have an advantage because the charge does not have to do a 90degree turn to exit under the reed, but can contine straight out the front.
The main disadvantage of the V reed setup seems to be <That it is a pain in the A*SE to make> that the oil film tends to stick the reed down- this can be worked around by reducing the overlap of the reed and the window.. but what a mission!

I do like the idea of the blowback of the stock reedy being fed to a neigbour- I think you are right in this one, Meowy


J.M