Hi Julia, Colorfab site says
"*Testing showed reliable results using the all metal hot-ends, such as the E3D and the Makerbot Replicator 2 hotend. Hotends which use a teflon isolator coupler can generate adhesion to the copper filament possibly leading to clogs and is there for not recommended for novice users yet."
I understand about the steel vs brass nozzle, I was going to look at alternative nozzles to fit your hot end, but would like to get the most suitable hot end
Thanks
Nigel