2 up with a loaded Hannigan Sierra (full cooler and a loaded toolbox + clothes for both of us and extra boots and shoes etc)
and the GL1800 ain't even working up a sweat and I don't tend to spare the coal. 1000+ mile days..
I actually hooked the trailer up for a year with the exception of taking it in for service (they talked me into a prepaid service plan)
I have a swivel hitch on the Hannigan (in the picture) and not on the Harbor Freight (youtube video)
and the ball and coupler binds slightly on the Harbor Freight right before the foot peg touches down
So if your a serious swervy curvy guy.. the swivel hitch is a good thing.. it does make the trailer about 6 inches longer though so (the swivel hitch also makes it where the trailer could flip and not turn the bike over with it... not that I'm looking to test that)
keep in mind it's back there, adjust your braking and make your lines just tiny bit wider thru the corners to keep it off the curb and outta the bar ditch.. plan a little more for gas and rear tires (probably wouldn't notice tire life if your a Dark Sider)