woods@weird.com (Greg A. Woods) tapped some keys and produced:
In practical terms I suppose it also depends on just exactly what filtering technology you've deployed, and just exactly how close it is to being overloaded. If you are already pushing your router's CPU too hard (and if your filters are done by your router's CPU rather than an ASIC) then obviously reducing your filter load will be in your own best interests and not filtering destination addresses against RFC-1918 will be one relatively benign way of reducing the filter load. However if your router's CPU is only partially utilised now (even if you push your pipe to capacity), then adding such destination filters won't hurt anyone.
Would routing them to Null0 not be more optimal? Pi -- conf t no ip-directed marketing drivel ^Z wr mem