Hi flessa, the main challenge is the backpressure on extruder and the filament between the extruder and the hotend (the filament in the throat area). A 2x line width usually is already a lot of back pressure. It’s over extruding a lot and completely relying on the plastic’s fluidity to spread out. Based on the assumtion of the nozzle “shoulder” would keep the plastic flattened. The higher the multiplier, the harder it goes and the less accurate the line width would be. Which is why you got 2.3mm 
I would say anything less or equal 1.5x would usually print easily, and anything below 2x is worth trying.