As it stands now 3.15 has a lot of free transaction space and that space is given first to transactions with the highest [age]*[value]/[size] correct? Would it be reasonable to make some arbitrary portion of the free space require [age]*[value]/[size] > C ?

Maybe set C so that a standard 1BTC transaction can get into the main free area on the next block. And a .1 can get in after waiting about 10 blocks. And make the area which allows [age]*[value]/[size] < C to let in about a dozen transactions or so.

Hope that makes a little sense.