These look like half-rack versions of the MPX-110.
I have one of those, and simple to set up and operate. It's also very limited in it's capabilities too.
It can only receive and broadcast on MIDI channel 1
Editing is no where near as in-depth as the MPX-1 or LXP-15. You are limited to the ranges of the knobs on the front panel.
There are a set of factory installed effects combinations that you can choose from with the front panel rotary selector. You cannot create custom combinations.
If those are considered the negatives, then the positives would be:
You do get Lexicon quality Reverbs, Chorus', and Delays.
These Harman-era Lexicon effects can be had at very affordable prices, as opposed the high end used Lexicon gear. I bought the MPX-110 for $45.00 USD.
Set up and use is as easy as stomp box effects, (which is what I consider these to be, in a rack case).
I hope that's helpful.
Harley