Purposely making the bi metal heatbreak work on an Ender 3 with one of the world's worst hotend covers for air flow. What we see so far. Retraction distance has a wide range of acceptable settings, we retracted up to 6.5mm with good results and no issues, we settled on 2mm the same we run our Microswiss hotends. The combination of retraction speed and acceleration had more of an effect, we suspect quick jerks cause the filament to stretch a little to high in the hotend. For a BMG on direct drive 500 acceleration at 45mm worked well. Heat was absolutely critical and most likely were most are having issues, the print temperature was approximately 10 degrees lower verse a standard Creality hotend. I never before considered how the standard Creality hotend leads to bad habits until now, it simply allows you to print at to hot a temperature. There is a reason why so many people can claim success with bi metal hotends on Creality printers, their fan is properly cooling the heat sink and they're not printing at high temperatures. I think this is one of the best things to happen to Creality printers but you're gonna have to forget most of what you learned already.