As an end-user, I’ve found it helpful to be able to print ~.8mm width out of my .5mm nozzle (j-head) to speed up prints and/or when additional perimeters would affect the translucency of the print (a lamp shade.)
@Elliot_Foster Those are valid reasons, but to my mind, raising layer height is more effective for both. You get less nozzle back-pressure so you can push higher volume flow rates through the extruder. And you get better optical translucency with nearly-circular strands rather than just thicker strands. (If you’re already extruding at 0.4mm high by 0.5mm wide and can’t go taller, then you can still raise feedrate without making the strands wider.)
@Ryan_Carlyle wouldn’t that negatively affect layer adhesion if you’re extruding (cross-sectionally) circlular layers? For my lampshade, I was doing .3mm layer height and .8mm layer width.
Also, this is a fricking beautiful hotend.
@Elliot_Foster Check the micrographs in the thread I linked a few comments ago, you’ll see how “circular” extrusion strands actually look. I have photos of a wide range of height/width ratios, all printed at the same volumetric flow rate.
The overlap the slicer puts in the strand pitch causes somewhat better void-filling and layer contact than you would expect. “Layer height = extrusion width” isn’t a very good idea, but pretty much any layer height less than 75-80% of extrusion width will work absolutely fine. I’ve done a lot of PC and t-glase prints at 0.6 wide by 0.5 tall, it’s gorgeous. You do have to slow your feedrates down to make sure you don’t exceed the hot end’s melt flow rate capacity though.
I suspect that a lot of the “setting X causes weak prints” issues people run into are caused by exceeding prudent flow rate limits so the filament is extruding colder than it should. The weakest prints I’ve ever made happened when I accidentally printed at 0.8mm instead of 0.4mm without dropping my feedrate 50% to keep flow rate reasonable.
This is a gorgeous little hotend 
But is the fan really able to cool it down for long prints and high-temp material? I never was satisfied neither with the throughput nor with the life span of these really tiny fans :s
Actually, you know what? I bet you you could build a very nice little 3d pen with this hardware.
@Jeremie_Francois We are probably going to use a 25x25 fan
@Mark_Ellison Super soon! Meeting with the hotend manufacturer today.