My reasons for disliking it stem from the fact that it sticks when trying to reengage snares, often requiring that you not only use the lever, but also simultaneoously pull up on the adjustment knob. The P85, like the P83 before it, and the modern P86 all have the same hole pattern. Therefore, the P86 will fit WFL and Ludwig Pioneer snare drums, Acrolites, Classic Maple, and Supraphonics. It will not fit the new Black Magics, the Epic-series, and possibly Rockers and Accent snare drums (I haven't tried the latter, but have heard they will not fit the hole pattern.) I do know for a fact that the P86 will not retrofit to a Black Magic, much to my chagrin.
Here is what the P86 looks like:
If you want to see how one looks, check these links to my snare drums that either came with the P86, or which I upgraded:
There are more on this site, but you get the picture.
One mistake many people make when doing the upgrade is to try using the screws that originally came with the P85, often installing them from the outside of the shell in and using nuts, or leaving out the black washers that come with the new P86. The following photos of my Ludwig Special Edition Satinwood snare drum show the correct way to install it and where the components in the bag go.
What comes in the bag
Inside shot of a wood shell showing the P86 screws
Outside shot of same shell showing where the screws go through the tapped holes in the backplate and a little of the black gasket peeking out (this is a stock Ludwig snare drum)
A close-up of the P86 (note the threads of the screws and a little better shot of the gasket at the right end.)
I hope this clarifies the correct way to install a P-86 for you. Life is too short to struggle with a P-85!