I recently got Patch Base to start editing my DX7ii via an iPad and it’s quite good. Looking at all of the parameters at once can seem visually cramped / daunting at first but with knowledge of the Yamaha FM architecture I’ve been able to understand a patch much quicker than I had by just diving through the menus; having envelope and curve visualizations per operator is so helpful.
The touch controls are a bit sensitive to get just right given their small size on screen, but the DX7 automatically goes to the parameter on the synth itself for easy editing with the increment/decrement buttons if needed. Plus the bank saving/editing will be nice for patch organization once I get that far. My iPad isn’t the newest and the app can be slightly sluggish because of it, but honestly all of my criticisms are worth making this synth easier to program (at least with my initial impressions). Chadwick was also super helpful via email in getting me over an initial hiccup in my MIDI set-up.
The other day my friend and I pulled up a random patch and started jamming for half an hour, subtly tweaking things as we went, and the app didn’t break the flow at all. Would recommend if you’re considering it.