PQI sent us two pairs of DIMMs: the first is the PQI 2-4200, designed for DDR2-533 and thus labeled as a dual-channel kit. It lists the rated timings as CL3-3-3-8.
We discovered an SPD programming error, however: the parameters for 266 MHz (DDR2-533) were stored double. We were able to run the DIMMs at CL3-3-3-10 and DDR2-533 with no hitches.
There is also plenty of overclocking leeway here. While we didn't reach DDR2-667 and DDR2-710 with fast timings, they were completely stable at CL5-5-5-15. Anyone who wants more will have to look to the DDR2-667 DIMMs from PQI.