Not a bad little bump.
DDR for the P3 isn't a total waste....
The P3 only has a 1.06GB/s FSB so no the CPU itself can't get at all  2.1GB/s worth of memory bandwidth, but AGP, PCI, IDE all use DMA transfers so the CPU can suck it's 1.06 and then split up the other half amongst the DMA devices.  Maybe it can't use all of the 2.1GB/s but it's not a total waste either.
The Pro266 is a pretty decent little bump for the P3 platform.