The Vactrol VTL5C2 seems to come closest to the CLM6000 in terms of both on/off resistance and response-time specs. On the other hand, Anderton tended to use the same device regardless of application, and in some instances I doubt his reasoning. For example, in the noise gate and compressor applications, and in the bi-filter foower, the CLM6000 and its equivalent are fine. In the case of the EPFM phaser project, though, the slow recovery time of the LDR in the CLM6000 probably gets in the way of the device being able to modulate very much at higher LFO rates. In that case, a 5C3 might be better. It has a larger max resistance but that's easily fixed with a parallel resistor. Response time, on the other hand, is something you can only make slower, not faster.