Lyman Johnson offers up a thoughtful analysis of the titular question in a new paper:
Abstract: This Article disputes the view - seemingly settled among scholars, judges, and lawyers - that recently - enacted statutes in Delaware legally permit fiduciary duties to be waived in noncorporate business associations. The argument is a rarity in business law because it is a constitutional argument, not one initially based on policy considerations or statutory interpretation, and it seeks to harmonize judicial review of fiduciary duties in noncorporate businesses with that in Delaware corporations, where waivers are not permitted. Delaware’s Constitution vests the Delaware Court of Chancery with general equity jurisdiction and powers of a kind that cannot be curtailed by legislative action. Consequently, neither the new and much-heralded waiver statutes, nor the private agreements they endorse, have divested Delaware courts of their traditional power and responsibility over fiduciary duties in limited liability companies (LLCs) or partnerships.
In addition to raising a serious and unresolved separation-of-powers issue for Delaware, the practical consequences of the argument made here are far-reaching. First, the argument casts substantial doubt on the efficacy of all those provisions in extant partnership and LLC agreements that seek to eliminate fiduciary duties. Second, the argument challenges the judges of the Court of Chancery to reassert their constitutional authority - and responsibility - over this field of jurisprudence and restore time-honored fiduciary duties to the law of unincorporated business associations in Delaware. The judges can exercise their inherent power to articulate fiduciary duties both where private agreements fail to address that subject at all and, where agreements do address the subject of duties ex ante - including agreements with waivers - the judges ex post should apply traditional duties in the manner a particular context may, to achieve commutative justice, equitably require. The key point is that, in every case, that specific determination must be made judicially; it cannot, by the constitutional nature of equity, be made a priori and categorically, either by the General Assembly or private contract or both together. Third, the law of noncorporate business associations in Delaware is, accordingly, far more indeterminate than widely believed and more indeterminate than the law of other states, thereby more closely resembling Delaware corporate law in this regard.
Larry Ribstein responds in a detailed (by blog standards, anyway) post. It's a nice example of how to conduct a scholarly argument: Thoughtful, respectful, constructive disagreement. He Who Must Not be Named could learn a lot from this example.