Regarding the newly added latter part of rule 3.1:
Any flying disc acceptable to both captains may be used, however non-white (i.e. yellow, orange, pink) discs are preferred.
Who "prefers" this, the rule-set? This seems to be an opinion, and I don't think it should be in the rules document.
Presumably this is for visibility, although it is not stated, based on the premise that a white disc is less visible than a non-white disc. Surely this does not hold true in every case on every beach, and certain colours could be picked which could be even harder to see than white in many instances (a "sand"-coloured disc).
Additionally, the grass rules don't mention anywhere that discs should be "non-green" (or that "non-green" would be preferred), so it seems like a pointless deviation from the grass rules.