I can actually. I have been using the Mesa Tactical products for a while. I have an 870 that I have used both the LEO adapter as well as the Urbino and before running the Aridus/Magpull stock I had an Urbino on the 1301. I too prefer a pistol grip shotgun as opposed to a regular stock as I feel I have more control of the shotgun. The biggest advantage of the LEO adapter is that it is very simple to adjust LOP depending on if you are wearing body armor or not. The Urbino does not have the adjustments except for slimmer butt pads and an adjustable cheek riser. I like the Urbino but find it to be a little cumbersome compared to the LEO adapter. The Magpul you can add or remove spacers, but it's not something you can do on the fly. The other thing I have and like with the LEO adapter is the hydraulic buffer tube as it acts like a shock absorber reducing recoil. In regards to the Law Folder, I don't see why it wouldn't work. It would add a little extra length to the stock but being able to adjust it, it shouldn't be a problem. I do not have any experience with the picatinny adapters, so I can not offer up an opinion.
Mike