Over the years I have always heard (and read from different sources) that monocrystalline are less friable than the polycrystalline version. The mono is also more expensive, which might indicate some superiority.
Two reviews from woodworkers and knife nuts:
I've owned an Eze Lap poly hone for about 10 years. It's in my desk drawer beside me right now. I almost never use it.
I've been heavily using a 4" DMT Fine machinist hone (actually 4 3/8") for over twenty years, it rides in my back pocket and in my current avatar. Based on proven performance, I'll stay w the mono version.
I would also love to see the results of lapping a Spyderco UF on the Shapton.