I have both Argon and Xenon and love them both dearly, spending half an hour a day with both.
The only things Id like to see is the step sequencer in argon to be variable between 16 and 32 steps, with all in between those two available so we could get some deeper rhythmic options, and also an analog-style looper to coexist with the current one which seems to be step-based.
I have the same request for xenon, except it is based on patterns rather than steps.
Even within the current limitations though, the sounds of this synth, the presets, and all the tweakability have made my day to day existence better.
Very great sounds and excellent controls.
AQ808 about ARGON Synthesizer, v1.2.4