I use the latest version (Loupedeck +) with Lightroom and love it. I have had it about 6 months or so. It is programmed by reference to Lightroom commands, and can be used with Capture One Pro and a few other programmes which I do not use. I have not tried using it with PM and suspect it could not work with PM without some new interface being written, but I am not a programmer and do not know. I can imagine it would be good for quickly going through images with the twist of the main dial and setting attributes at the click of a button, quicker than using a mouse or conventional keyboard.
There are various videos on YouTube about using a midi controller to control Lightroom, and I imagine Loupedeck works in much the same way under the hood, but with nicely labelled buttons and keys by reference to Lightroom terminology. If it could be linked to PM for image advance, ratings, selections etc., I would certainly use it that way, but maybe if Loupedeck could be made to work with PM, so could a midi controller.
Graham
Graham