I use the ECM-3 to connect the H6 capsules to my Zoom F8. The ECM-3 does what it is supposed to do. However, it is slightly awkward that an extension cable is actually more expensive than the mic it connects.
I think that Zoom should offer some kind of discount for owners of the F8.
Quality is good. The cable is a bit stiff, especially compared to traditional mic cables. This makes it difficult to drape/run, and it feels more like a piece of steel wire than mic cable.
If you need to connect Zoom's capsules to an F8, then you need this cable. It's a sad fact.