These newer powders favour the '06 more than they favour larger cases. In other words, the burning rates of the newer line of powders are made for cases smaller than the belted cases. It's quite simple, really.
There is one new slower burning powder, but it does not work as well in the 2 1/2" magnum cases as it does in larger yet cases.
The data I have presented is straight out of the loading manual with pressures as well.