The MiniGrip carries much smaller in the pocket and has a much "heavier" blade profile, especially the tip. It is a much smaller knife overall, especially when closed, but if you compare cutting edge, it only gives up about a 1/4" to the PM2.
The Para is a better slicer, has a much larger handle (remember that bigger in the pocket?) which will be better IMO for prolonged heavy use, and a very pointy tip. When thinking about hard use, the Mini has the better blade, the PM2 the better handle. The handle on the Mini is fine for everyday use, but too small for hard use.
The Mini uses 154CM unless you get the Ritter version (which is a better slicer) that comes with S30V, like the PM2.
I've EDC'd the MiniGrip for well over 5 years now and nothing has been able to knock it out of my pocket. I have M-L hands and love the ergos, love the Axis lock and love the blade design. I also like that it gives me one of the best cutting edge to handle ratios I've seen. I recently got the M390 PM2 because I just had to see what all the fuss was about and it is a good knife. Great ergos, but really poor blade/handle ratio and the tip scares me a little for some of my EDC tasks (prying staples for example).
My main complaint (and the reason it didn't replace the Mini in my pocket, as much as I wanted it to) is that it just takes up too much room in my pocket. This is more of an issue depth-wise than width-wise (though it is wider, too). I can't move my keys around out of the way to get at my change, or my other keys, etc. I will look at ways to get some carry use out of the PM2, but year after year the MiniGrip has knocked all comers out of that right front pocket. It's just about perfect for me.