In the post Kearfott on Washingtonianus the thesis referred to apparently identifies "1520 discrepancies that occur in the critical apparatus of the 27th edition of the Nestle-Aland Novum Testamentum Graece with respect to the biblical manuscript Codex Washingtonianus". In the comments, Jan Krans makes reference to the volumes by Reuben Swanson which I thought I would highlight.
In an appendix to his volume on the New Testament Greek Manuscripts on 2 Corinthians, Swanson refers to problems in the apparatus of Tischendorf (169), UBS4 (51), Nestle-Aland27 (148), and those in Kenyon's transcription of the Chester Beatty Papyri, all in relation to 2 Corinthians. A large number of these problems/errors occur in areas where the editors of UBS4 and NA27 try to fill in blanks in the lacunae in the manuscripts. It is this "filling-in" which Swanson seeks to question. Swanson also claims to have identified 129 misleading and incorect variant readings in Kurt Aland's Arbeiten zur Neutestamentlichen Textforschung. Text und Textwert der Griechischen Handschriften des Neuen Testaments. II. Die Paulinischen Brief (Walter de Gruyter: Berlin/New York, 1991).
In a comment about Kearfott's thesis on Washingtonianus, Peter Head makes a good points that one should take into account the aims of the apparatus in certain editions (e.g. deliberately not comprehensive and attempting to simplify the evidence at points). I would add that speculating about lacunae is fine, as long as you tell people that you're speculating. This raises the question of whether Kearfott and Swanson have misread the strategy and aims of the apparatus in NA27 and are simply being pedantic, or whether the apparatus that we are accustomed to using really do need to be double checked, more detailed, or overhauled.
One thing I do like about Swanson's volume is that he chooses Vaticanus as his base text rather than an eclectic text and he (rightly) questions the assumption that "an eclectic text is superior to an actual manuscript text that had been scripture for an early Christian community" (p. xvi).