I would like to suggest
1) Sequencer's Width getting a signal input.
2) Sequencer's Range getting a signal input.
3) Option to trigger the sequencer via Aftertouch (while Key Trig is off)...
3a) Different Aftertouch trigger modes:
Trigger and run normally
Trigger but stop when Aftertouch is no longer pressed
4) Option to flip the sequencer's steps horizontally (left/right)...
5) Envelope 2's Release getting a signal input.
6) An option to sync the LFO to host tempo.
7) LFO Noise getting a signal input.
8) Aalto getting the output limiter feature from Kaivo.
9) A simple LPF and HPF either in front of the Reverb for the audio that's going in, or for the wet Reverb signal itself.
The filters could be stepped and have fixed frequencies. This wouldn't limit their usefulness but would avoid the necessity of a number display.
Think something like 5 stepped positions, for example Off, 40, 100, 200, 400 Hz for the HPF and Off, 18, 12, 6 and 1 kHz for the LPF.
10) Adjustable pre-delay for the Reverb (like Envelope 2's delay). Maybe with signal input.
TL;DR – I've concocted a gui mock-up, brutally cramming in all of my suggestions: http://i60.tinypic.com/2up72ao.jpg
OK, thanks for the feedback. As you found out, it quickly gets cluttered, which is always a challenge. But I'll mull these ideas over.
As far as triggers, I think the move is to go to a dedicated trigger input like Kaivo has. Then you can use it form aftertouch or whatever you like. Same with LFO sync.
The reverb tune is kind of a cool idea, I like that it's a one-knob reverb now like the Arp 2600 etc., but there is room for more controls if they are just the right ones. Maybe hidden behind an "Expert" panel for not modulatable stuff, is my current thinking.
The dedicated trigger in Kaivo is great. I wasn't aware of it because I haven't spent very much time with the demo yet.
I like the panel idea for less important or one-time setup type parameters very much.