We've received a new "V2" hot end from Zortrax! Unlike the all-metal V1 design, the V2 includes a plastic (probably PTFE or PEEK) insert in the stainless steel feed tube. Testing shows that the V2 is much less prone to jamming when used with PLA or PLA/PHA, even with a standard 0.4mm nozzle, and we highly recommend its use.
The V2 hot end can be ordered from the Zortrax Store: https://zortrax.com/store/upgrades-and-parts
V2 Hot End Top View Showing Plastic Insert
V2 Hot End Side View Showing Extended Insert Section