Leica is ... quirky.
I have both an ER (2.5-10x) and an ER 5 (4-20x). The ER 5 is assembled in the US and supposedly lacks a lens weather coating that's applied to the ER series. On the plus side, the glass on both is delightful. Truly good stuff. On the not so great side, the documentation supplied for the IBS reticle on the ER was incorrect and the online calculator provided incorrect results. I emailed their technical support and was ignored.
My conclusion is that it's a flawed product in that support is highly questionable, but it's also a high quality product. My personal decision was that I was willing to take the chance on the support issues if the price was sufficiently discounted. FWIW, I like both scopes.
Edited by syncerus (01/14/18 07:59 PM)
Edit Reason: gramma
NRA Patron & DSC Lifer