While I fiddle around with my own controller design, I needed a conventional one to test locos with, so I'd know if any issues were down to the loco or due to my programming. So @AVS1998 very kindly sent me one (in return for a few custom 3D printed bits) and now I can see how various chassis are performing.

The Manning Wardle works beautifully - though being an RTR chassis, I'd expect it to... The standard Hornby 0-4-0 regearing project runs quite nicely, nice and slow and controllable but still a bit loud. The tiny Hunslet is also a bit loud, and doesn't pick up too well, mostly down to it weighing virtually nothing, so I think I'll swap the gears for a belt drive and see how that gets on. It would also help if my test track was actually flat...