I'm pretty torn on this one but since this horse is almost certainly true roan, I'm going to say yes for it- however if anything contradictory comes up (like for say he is eventually tested for roan and is found to not carry it) Roan will be removed from IDs since I can't find a single other RID who appears classic roan. One of his fillies who is registered as grey only has him and a mare listed as chestnut for parents, so I'm not 100% convinced he isn't a type of oddball grey. However, until proven otherwise, roan is accepted in IDs.
It was an indeed an oversight- when we manually put the allowed colors for every breed in the autoreg system, some inevitably got missed or put in wrong (only to be expected with well over 200 breeds!)
If you (or anyone) finds any colors that are missing from breeds that they were accepted to carry before the automatic registration transition, just message me so that I can re-add them to the system. Tobiano has been re-added to Drums, thank you!
It is very likely W, yes- probably W20 to be specific. GRPS can be outcrossed to Welsh stock, which do carry SB1, so it's possible that they have it; but no way to confirm it without tested proof.
SB1 is actually in the family of White Spotting genes, which is why they are so similar; SB1 was isolated and named before much was known or understood about white mutations, and before we realized that this family of genes caused both extreme ends of the white expression spectrum, from minimal white markings to solid white horses (neither of which anyone would call 'sabino') and from there we took up using White Spotting to name this family of genes. Think squares and rectangles- all SB1 is a white spotting gene but not all white spotting is SB1. It would be very helpful if they renamed SB1 to W0 or something, but since that seems unlikely we have to understand the difference!
Here is a fabulous article that explains why we use this terminology for the white spotting family, and some other interesting facts about W and SB1 genes, if you're interested in learning more. And please, don't hesitate to post again if you find proof of any breed that has been tested to carry SB1!