I don't think that improving dual processor support must be a priority. I have tested this topic at user level, and eventroug dual CPU can theoretically double the speed of our computers, there is a lot of bottlenecks that dramatically limit the success of multi CPU support. Even the faster 166 Mhz system bus on a MDDs is a bottleneck for most dual CPUs apps, let aside slow ATA 66 or ATA 100 Hard Disk ...
As I use to tell, if you wish speed on a Classic Mac install a nVidia GeForce4 Ti 4600, a SSD with a SeriTek 64 bits SATA PCI card into a MDD single 1.25. And finally add an xServe 1.33 CPU and overclocked it to 1.50 Ghz...
... but don't bore with dual CPU's ... IMHO