Tyndale House at Cambridge University has released a downloadable (for some) edition of Tregelles' 1879 Greek New Testament. Here is what they say about why this publication is still applicable today:
"Why would one bother with a Greek New Testament printed in the 19th century? Has it not been superseded by improvements, new discoveries, and a finer methodology? Is this text not simply a relic from the past, with mere curiosity value, but of no further importance?
"First of all, in order to understand where the textual criticism of the New Testament is at the moment, it is of crucial importance to know how we arrived at this point. The principles Tregelles laid down, and the result of these principles (alongside the evidence he provides for and against his choice of text), are part of the history of the discipline and form an important contribution to that discipline.
"Secondly, even after 150 years, Tregelles's edition pays attention to variants that are not recorded in the Greek New Testament mostly used in the universities and seminaries, the Nestle-Aland 27th edition. Many of these variants are not yet covered by any of the current major projects in the textual criticism of the New Testament (though many of these will be found in Tischendorf's edition and the work by Von Soden). Though it is likely that this situation will change in the coming decades, there is still real value in the collection of the evidence.
"Thirdly, independent voices need to be heard and not forgotten. It happens all too often that students of and commentators on the Greek text find safety in the consensus text, tacitly accepting the methodology and assumptions of the day. Dissenting voices from the past such as Tregelles, who earned the right to be heard by means of his long exposure to and interaction with the evidence and methodology of the discipline, can guard us from a misplaced confidence.
"Fourthly, Tregelles can arguably be described as a theologically conservative scholar. There is a sense in which this conservatism shines through in his method. Tregelles had come to the conclusion that any speculation and reliance on a constructed history of transmission was a dangerous thing to do, but that the only sure ground for establishing the text of the New Testament was to limit oneself to what can be seen in the manuscripts as surviving artefacts. Tregelles combined this notion with his conviction that theology should follow from the text, and that therefore he stood under an obligation to print the text established to the best of his abilities."
This last point is perhaps the most important for me. While I will not necessarily agree with SPT's conclusions or even his approach, the fact that they were couched in a firm belief in the authority of the Scriptures speaks volumes.
That being said, it is also interesting to see Tyndale House's frenzied but futile attempts to eliminate scribal errors in this edition--they couldn't even avoid making one in the process of writing two sentences about how hard it was:
"It turned out harder than imagined to avoid transcriptional errors. . . . These two transcriptions where then compared against each other and the differences were reconciled."
The very defects Tregelles' text exihibit, having been typeset 150 years ago, are with us still:
"Tregelles used a series of identical printings of the then standard text of the Greek New Testament (the Textus Receptus) as the basis for his collation of manuscripts and ascertaining the text of his edition. It is almost inevitable to avoid errors caused by this base text shining through, and these are particularly visible in the errors of the printed edition. . . . And in Luke 19:41 we find the conflated reading ἐπ᾽ αὐτῄν (EP AUTHiN), a combination of the reading of the Textus Receptus, ἐπ᾽ αὐτῇ (EP AUTHi), and the reading Tregelles must have preferred, ἐπ᾽ αὐτήν (EP AUTHN).
"The procedure that was followed was to have two people, independent of one another, adjust existing electronic editions towards what was seen on the photographs on screen. . . . Neither electronic text proved to be completely free of accentual errors. . . . After this a print out of the transcription was compared against the actual printed text which resulted again in the correction of details that were missed at the first stage. Finally, a last proof reading of the transcript was made in conjunction with the "Table of Changes and Corrections to TNT" in which special attention was given to issues of accentuation and consistency. Especially in this phase, the expert knowledge of Dr P.J. Williams filtered out a considerable number of glitches."
And all types of scribal error are likely present, even orthodox corruptions in the TNT2 redaction:
"I am all too painfully aware that the TNT and TNT2 we are releasing will contain some errors in transcription of some accents, punctuation, and possibly even of a word or word order."
Plus ça change, plus c'est la même chose.