Oh, I know someone who played keyboards in the recent Cats tour and I *thought* he had said they emulate sounds that originated on the DX-7 back in the day, but now realize I got what he told me mixed up with something he said about Les Mis. My bad.
I really like the synth sounds in Cats, as well. They are so distinct, it's hard not to recognize them and give the show a trademark/signature sound. I LOVE the Les Mis keyboard sounds but the 10th anniversary updates in 1995, in which those original patches--like the ones heard in my track below--were replaced with more neutral sounding ones that mimicked the orch's existing orchestral instrumentation, are aiight, I guess. At least the patches were the only things they altered of John's orchs at the time.
I'm having a good day. DON'T get me started on what they've done since! LOL.
Recreation of original John Cameron orchestration to "On My Own" by yours truly. Click player below to hear.