My opinion:
New UI is promising. As long as major functionality isn't removed, I think it's a great idea.

I really like the increment/decrement button idea. It also provides a fallback in case one's slider dies.

I'd rather keep all 4 banks editable than add a ton of mod destinations

Patterns should be stored with patches, but it isn't the end of the world for me either way.

I like having all the parameters for "sound tinkering". These features were why I upgraded - they unlock the potential of the JX-3P. I've always thought of this mod as a way to turn a JX-3P into a kind of "pseudo-Jupiter", and as long as it gets close to that, I'm happy.

[For reference, the Jupiter 8 only has a single LFO and rather limited modulation options; The Jupiter-6 has 2 LFOs and both can modulate the VCOs simultaneously, but I believe LFO2 is only triggered from a button]

I thought the original proposed destinations and parameters were fine/sufficient. Being able to assign both LFOs to the filters or oscillators is not something that is particularly important to me, though I would use it occasionally if available.

My top request would be to add pulse width modulation to at least one oscillator, but I suspect the circuitry doesn't support it.

Secondary request would be adding a resonance parameter to the HPF (that's a unique feature of the Jupiter-6), but again, I suspect the circuitry doesn't support it.

The complexity of the UI has more to do with the DX-7ish parameter-select-and-edit-value interface than the number of parameters or how they're laid out. The "vanilla" JX-3P had to put a map on the front panel, and it is still pretty confusing until you memorize the arbitrary assignments. This is all sort of academic for me because I plan to do all my programming through my Cubase panel via MIDI messages.

As long as it will still receive MIDI and respond to controller changes, I am happy!