Does the cooling fan make a difference? Yes...

Quick answer to if the cooling fan made a difference is yes. I made the famous octopus yesterday and it was the first time I had consistent extrusion throughout the print.

Clean octopus print from utilizing my cooling fan

I can't really think of a con to adding a cooling fan to your hot head. Even if you don't have issues majority of the time. The plastic stays cooled higher above the nozzle so

• I did not get the extrusion issues on my hob bolt with material getting soft
• The plastic is melted only at the nozzle so it makes it less "stringy" and I had cleaner lines and layers
• Possibly prevent ever overheating (flow is pretty low though)

I have not tried with ABS but this helped my PLA prints. Originally I was a little worried it would cool too much and the resistor would not keep up but my mount is high enough it does not flow over the metal nozzle and there were no issues at all. Overall I say a small $ for the benefits. The fan only costed me about $3-4 and I had rest of material laying around.