As already mentioned, LDR's are fairly slow - and in Ron's case bulbs greatly more so - which was an advantage, a bulb/LDR combination gave pretty good attack/decay for AGC etc.
I also built an LDR/lamp attenuator using the concepts described above. Boy, that was years ago!
The most difficult part, if I remember correctly, was to match the input voltage vs attenuation in the two channels across the control voltage range. LDRs have a wide, wide tolerance.