While the GR-1 is an excellent granular synthesizer - opposed to the S-4, which only features rather limited granular effect on top of a rather simple sampler - I never got used to the UI of the GR-1. And the effects and filter were so limiting, and with only a stereo out, there’s no way around that for multitimbral use.
I really don’t mind a bit of menu diving, but the structure of the menu and the navigation with one knob didn’t work out for me. The way knobs are assigned either to effects or the filter, and I had to go to the menu to change that drove me nuts. No MiDI control of all parameters either, so I could not work around that. Navigation of the mod matrix is really tedious, too.
Last but not least, for a multitimbral instrument, faders and knobs don’t really cut it, encoders work so much better.
And it was so easy to accidentally lose sounds because I hit the wrong button when triggering sounds.
Most of that might not be so much of an issue when one can afford more time for making music, but sadly, I can’t these days.
I must admit the interface of the S-4 is not perfect either, some of little inconsistencies and odd choices, overall it just works better for me, and the number of modulators and effects make sculpting sounds a lot easier, even though the sampler and granular effects are a bit underwhelming, and can’t really compare to the GR-1.
Hadn’t heard about the re-write when I wrote that, so maybe it will change things. But most of the UI will probably stay the same.