Hey, Tim, we have quite the running novel here. I would think that the Eclipse would be the better investment if sound / effects quality was the primary consideration. It's certainly versatile in routing, internal controllers, and sheer number/quality of effects. I have no idea what may or may not be transmitted over MIDI, though.
The Lexicon's audio effects are very good … for 15+ year old technology. I wouldn't try to compare the pitch shifting to the Eclipse. But the forethought on its MIDI implementation is astounding. I don't think that I've seen anything like it; including most any keyboard controller. As arpeggiators go, the one in the MPX-1 is fairly basic. In software, something like Cakewalk's Sonar / Project5 arp would run rings around it; feature-wise. But you can "extract" relative CC values from whatever notes are transmitted. For example, I can send a MIDI note from the FCB-1010 switch, have it arpeggiated in the Lexicon, and have CC messages cascade harmonies in the PitchFactor.
Another very configurable arpeggiator – actually, 4 arps that transmits MIDI – can be found in the Alesis Ion / Micron. These aren't going to output any CC values (notes/velocity only), but I mention it as an example of one of the deeper arpeggiator designs. For those interested, there's a .pdf manual at the Alesis site that describes the features in detail.
As for the MPX-1 MIDI controller arsenal, I approach them like building blocks; just like the modular synthesizers that they sprung from. These can be used to infuse the characteristic "shape" and dynamics over any parameter in the destination hardware. Which is any control, in any stompbox/processor, that's capable of MIDI reception. I start with a feature that I could use, and assemble those 'building blocks' to get there.
Examples: I want to have detuning sweep over a narrow range in PitchFactor's 910/949. No internal modulation is available. An external LFO sine wave varies Pitch A, with its reciprocal (same LFO) controls Pitch B. If the same setup were applied to level or mix parameters, it would add ping-pong panning or tremolo to the algorithm. Or perhaps it would be used to add vibrato to the PF's Harmodulator, while still retaining use its internal envelope. Or use the internal sine waveform, and apply an external MIDI envelope over that.
In the MPX-1, any MIDI modulator can modify any other MIDI modulator. So, for example, an envelope or ADSR can fade in the depth of an LFO, which itself can be 'sampled" by the sample & hold module into discrete steps. That can end up in a guitarists' "bend to vibrato", widening vibrato depth (triggered by playing dynamics), or in a randomized realism that humanizes a too-perfect LFO waveform. I've used vibrato as a common example, but the sky's the limit. I use triggered chromatic "pitchbends", harmonies that sweep between scale degrees, ultra-thick detuning or dynamically-controlled chorusing, envelope-controlled scale changes, etc.
The S&H and Random modules can provide "sequences", of a sort. Random steps at a given rate, or anything the sample & hold can process. For example, a Ramp Up through S&H yields an upward staircase of synchronized steps ("chromatic bend"). It's somewhat limited. But with a sequencer … that's completely programmable. Think of the Pitchfactor's Harpeggiator on steroids, but with every level of every rhythm, every pitch pattern, and every effect being user-configurable at every discrete "step". You'll definitely get more bang-for-the-buck out of a software sequencer. I use several of them in a recording environment. I haven't had the reliability I'd like from a laptop in a live venue, though.
In fact, I started out compiling handwritten notes on the PitchFactor's CC values, until I thought, "This is ridiculous. I can compile and store all these values in a software sequencer, and get visual feedback along the way. Once." The task is daunting, though. Some Pitchfactor parameters utilize all 128 CC values to trigger a discrete setting for ONE knob. There may be three variations over that one knob x 128 values. Great. Nine more knobs to go, multiplied by ten algorithms. So, I'll take any help that I can get; if only "beta testing" the results before I commit to MIDI files and .pdf charts.
But the payoff is clear: Anything found in [name your poison: AdrenaLinn III, Eclipse, Voiceworks, etc.] that has a comparable base effect in an Eventide stompbox can be simulated, or recreated completely, or warped into a unique, uncommon configuration. User-definable "scales". Slicer effects; user-configurable. Adrenalinn's sequencing over filters, micro-delays, & levels. Complete key / scale / chord overlay changes. Quadravox-Harmodulator combinations. Waveforms & glides & stepped levels & sequence bursts all available to a single preset or mode in the targeted device.
A reference chart allows single CC values to be put into pedalboards for repeatable results. As MIDI files, single CC values can be combined in-the-box into sequences of CC values; each of which adjusts a parameter on an Eventide stompbox; hands-free. After my initial hit-or-miss approach, I'm concentrating now on the Diatonic / Quadravox scales. Some of that will transfer over to the more complete documentation later on.
Believe it or not, I probably missed a few answers and a ton of techniques here. This is an omission from my previous, lengthy reply. In the 'aux switch controlling the expression pedal' area, we missed discussing a subtle (but powerful) distinction. Were you to assign an aux switch directly to a parameter knob [KB0 > TIP], the high and low values are triggered by alternate foot presses. Using [PDL > TIP] (at least in the PitchFactor, and with my switch setup), I get the maximum value on a switch press, and the minimum value upon release of the switch. There are occasions (especially 'live') where a touch-and-release action is more desirable than alternating taps.
As for the "why" of having a setup like this, it's simple. I don't want to sound like anyone else. I consider this to be creative expression, like any other aspect of music. I've never been much of a "preset junkie". Nothing against anyone who is; in fact, I've done some commercial preset collections for software synths and hardware. The power is there in Eventide stompboxes and rack units, and I want to tap it. Entry level only requires any single device that transmits MIDI CCs. After that … fold in another 'building block' that fulfills a real need.
