I use a Tour-X on a 1200GS with a NN cockpit screen and find it fine at all speeds (just need to be careful that you don't 'lift your head' when returning to straight ahead after life savers - that's the only time I've found that the peak catches).
I've found it OK at speeds up to about 115 mph (though I don't think you could sit at that speed all day with the cockpit screen anyway).
I've even sprayed the top of the visor to 'black out' lower than the peak does - helps a lot with the low sun on my way to, and from, work.
Overall I think it is a brilliant helmet - though I wouldn't use without ear plugs (especially with the Remus Genesis can (and headers) which has very little baffle).