Well,
I think that if you want FM then MBFM can do it for you.
If I remember well more modern FM synths like FSR1 can modulate operators with PCM waves so can create
more complex sounds.( so the pad in the video seems audio silk )
Now I have both TX81Z and MBFM and it seems to me the sound are very similar ( effectively they have the same operators number , the same waveforms and probably the same modulation algorythms )
As I will finish my control surface I am very motivated to port the sound of my TX81 on MBFM for a comparison.
Regards
Antix