The OTA itself in both ICs is virtually identical, and output buffer appears to be a Darlington in both in the National Semi datasheets I've got here. The difference is in the linearising diode affair at the inputs of the OTAs. I've used both the '600 and '700 in the feedback attenuator topology with identical results.
I've also used them in another limiter topology that uses two audio paths with one inverted with respect to the other, and the two mixed by OTA gain cells. This further reduces the distortion contribution from the OTAs, and allows me to use level-dependant pre-emphasis (to squeeze the last possible dB out of the audio path!).