Just popped into Hattons and tried H1410 and H1411 on their test track. H1410 relatively smooth but slipped to a standstill on slight changes of gradient, H1411 was appreciably smoother and gradient might as well have not been there; no effect on performance.
It was a smooth runner even at slow speed, no nasty noises, so its now sitting on my rolling road running in; will keep fingers crossed!
The lady serving was very helpful and testing each model was no problem.
Best wishes
Nige