tl;dr: I like the mosquito hotend

Reliability

I purchased the Mosquito hotend because I often had issues with heat creep during prints with PLA. In the last 200h I had not a single issue with heat creep.

I was a bit concerned about the mechanical properties of my extruder body (PETG) during prints at temperatures around 240°C with closed printer housing. The temperature of the heatsink can rise up close to the glass transition temperature of the PETG. 

By now, nothing happened. The hotend still sits firmly inside the extruder body. 

Print quality

I could not see any difference in printing quality compared to the stock hotend (E3D v6).

tbd: It should be possible to print models with a very fine resolution in Z-axis without the risk of heat creep (increasing the resolution = decreasing the volumetric flow rate) 

Service

When I tried to play around with wood filled PLA, once it resulted in a clogged nozzle. Because I did not recognized it directly, the filament was grinded by the hobbed gears, so I could not remove the filament by the unload function of the printer. 

To remove the remaining filament I just removed the nozzle (with one hand) used new filament to push the remaining filament through the hotend and screwed in a new nozzle (with one hand). 

Finished! 

Compared to the stock hotend, it is very easy... almost fun.

Conclusion

I have considered to buy the Mosquito hotend for a long time. Finally I bought it and I do not regret it. I had to pay a lot of money for the hotend, but it is worth every € I spend. 

I am also happy, that I could improve my designing skills during this project. 

I made some quick measurements to check if the cooling of the hotend is working properly.

The measurements were made during a long print with PETG when the temperatures were in a steady state. The thermocouple for measuring the heatsink-temperature was attached close to the lower edge of the heatsink, where you can expect the highest temperature.   

First I made a measurement at room temperature, then I closed the heated housing of my printer and made measurements at elevated temperature.

Please note: Month ago I replaced the Noctua printer by a Sunon MF40100V1-G99-A for better cooling performance.

Ambient temperature [°C]	Hotend temperature [°C]	Heatsink Temperature [°C]
25	240	approx. 30
45	240	approx. 60

Conclusion

The thermal contact between the thermocouple and the heatsink is far away from perfect, thus the real temperature of the heatsink will be slightly higher than the measured temperature.

As expected, the cooling at room temperature works better than the cooling at high temperatures.

Because the extruderbody is made from PETG (continuous operating temperature ~65°C), I would not recommend to print large parts with hotend temperatures above 240°C with closed printer enclosure.