I'd say that this guy will almost entirely lose his white spotting. But - he is a carrier of Mottling! So it comes down to size and other positive traits.
With his nice, bright light color, and yellow legs, he could be a very helpful cross to Speckled Sussex hens, if you found hens with an excess of spots. The first generation chicks would look like Speckled Sussex - as the pink legs and dark mahogany color take over.
The Mahogany color is very difficult to breed out, but eventually, you might be able to "pull" this boy's light buff color out again. (As icky as it sounds, for example breeding him to Speckled Sussex hens and then crossing the daughters back to the father, you could get Mille chicks within one year, most likely!) And the recessive yellow legs would start to show again. It would be a matter at that point to pick out the lightest and most spotty chicks. (And then of course cross those to something totally unrelated to diversify bloodlines.)
So he could for sure be helpful, it all depends on what else you had? He'd be good on very spotty Speckled Sussex hens.
For crossing with New Hampshire Reds, I'd prefer to start with a "super spotty" Aloha rooster instead - or even a nicely marked Speckled Sussex roo if someone is starting without Aloha stock.
I know a local breeder whose breeding stock is high quality (no big hatchery lines). I actually have some of his Speckled Sussex eggs in the incubator right now.