Well...I think the MP1 Channel has been a very good idea from ADA, in the "full of stuff" pedalboards era.
Rack units were very popular (and expensive) in the '80s and '90s, but Pearl Jam and other (great) bands redefined the whole concept of tone and sound from then on.
I assume guys at ADA asked their self something like "how can we bring MP1's tone back today?" and they found the answer building that pedal.
I would love to have one to nail it in my pedalboard and have my MP1 tone everywhere, since I would not carry a full rack out of home anywhere.
Furthermore, it's not easy today to find a full rack MP1 in good conditions and at a reasonable price...so, if you have one, the best you can do is to preserve it and enjoy it at home.
I've been lucky a lot with mine...but a second one I bought ("as new" said the seller...) was a total mess and full of issues, so I ended up selling it at 50% of what I paid it to a guy who had the project to repair it.
A third one gone lost due to the stupid driver of a very poor courier service, but this is a story I prefer to forget (but it is another risk that must be considered).
As I wrote, it looks the Channel has a tone that's very, very close to the one of a MP1 with MDRT transformer and that's a plus, 'cause you get one of the best mods for free.
The high voltage increases tubes dynamic range, giving you back a more clear, detailed and defined overall tone.
To me, this is an important plus.
Of course, I would be more than happy to find one of this toys at a low price...but the main problem is that it's very hard to find one used...and, as Jerry stated, today shipping became a real pain in the ass, especially from US (I became crazy to find a particular battery for my Digitech Twin Tube at a good price and someone who would ship it to Italy at a rate lower than the selling price
).
About pedals, I spent years and years buying, selling, testing, re-buying and re-selling pedals before I found the right ones (TC Electronic...I love you!)
Drive/Distortion pedals made me go crazy...I just found my rest place with Bogners, at the end....but those are preamps, not simply overdrive or distortion pedals.
And that's a big difference...the same difference that I bet applies to ADA MP1 Channel.
About compression...let's scoop mids a little bit and taste it...
When I had my MP1 back after mods, I found that, to have a tone close to the one I had with original transformer, I had to scoop mids a little and reduce a bit highs and presence.