That's not at all surprising. PBR would be pretty hard to push
into a hardware forwarding path.
Not impossible, but certainly challenging.
Doesn't the SUP-720(PFC3B) support (some forms of) PBR in hardware ?
As has been pointed out to me privately, the SUP-720 does flow cache
PBR support. Now, if you consider a flow cache to be acceptable
performance, and the flow descriptor fits within the policies that
you wanna write and you fit within the performance boundaries of a
SUP-720, well, that may be a suitable solution.