Hexagon Ø0.4mm hotend, Ø3mm PLA at 205ºC. The hexagon heatsinks/fans seem to be working well as I can touch them right above the fiber/kapton insulation and they are quite cool.
I have Pololu 1209 NEMA14 motors. Voltage on the A4988 drivers is 0.32-0.325VDC which if my math is correct is ~0.8A. When it skips the entire belt path rotates backwards including the metal gear and motor shaft (presumably under the force of the filament pushing back on the hobbed bolt) so I don't believe there is a belt or gear anchoring issue.