First because the same rules should apply to neutrals who are also lawyers. Second, at least in areas of the country like the SF Bay Area, more and more lawyers are becoming full time or at least independent neutrals, severing their law firm ties, which is the price of avoiding the law firm conflict. I am especially troubled by Comment paragraph 2 to 4.1, which is disingenuous at best. I would simply exempt negotiations from the rule. I do not believe one can write a rule that successfully draws a line between the duty of candor and the ability to puff in negotiation.
Negotiation is inherently deceptive.
There's always something being held back. I wouldn't change 3.3, but I'd change the 4.1 comment. All of this is waivable and in mediation, familiarity with the participants and especially the lawyers makes resolution easier. I'd like to think about arbitrator disclosure too. Indeed, I used my admiration of him as capital during the mediation.