nice to hear you invested in a Lexicon PCM80. Those oldies but goodies still sound amazing especially if it is a multi effects processor. I have a Lexicon LXP15 whose 2 inverted gray encoders I have to replace with non-inverted ones.
In case of fiddling with hardware synths.you might look for the Mod Duo X as it has CV input and output as well as analogue stereo I/O. This would be the way I would go.
But as you point out regarding the development of the Line6 Pod HD500X, I think the mod developers (and users!) team has still a lot to do replicating and inventing (combinations of) effects that are completely new as well as old ones.
If we manage to invent some weird but usable effects out of plenty possibilities we got at hand we can push moddevices definitely forward.
In case of playing with modular synth parts inside the Mod Duo or Mod Duo X.
Aurelien Leblond has ported the whole [Alsa Modular Synth package](https://github.com/blablack/ams-lv2) to lv2 so you can build your own synthesizer parts within.
These are 66 different modules including oscillators, analog memory,
Bitgrinder, CV sources, Delay, Dynamic Waves Oscillators with 4 to 8 voices,
Envelope with Delay, Hold and timescale, Percussive Envelope, VCFs, Moog LPF,
FFT vocoder, Hysteresis, Inverter,
LFO with frequency, phi, BPM Tempo and waveform, a multiphase LFO,
2,4,and 8 channel mixer, Ring modulator, Slew Limiter, 8 to 32 step sequencers,
and such to name a few…
I am just a german user who wants to explore the capabilities of the mod duo family to the max and to program pedalboards and effect combinations that others may use or change to their benefit. In my view the mod duo would benefit from a digital I/O in form of SP/DIF cinch or ADAT Toslink sort of connector or USB I/O, I even could imagine an AES67 “Audio over IP” or AVB version, if that was possible. I know there is an implementation of an audio network within linux. But these questions would be better sorted out in another thread that covers future vision. Sorry if the last part of my answer got a little too off-topic…
We all only can give our input, but I think this will be heard.
God bless, Marius