... the much more accurate explanations of "No. This is completely Second Mode (Plagal Second Mode) with the same scale, just a different version of Second Mode (Plagal Second Mode).
From a theoretical standpoint, I would be very hesitant to refer to the hard chromatic hymns of second mode (anavathmoi, katanyktika, etc) as being "in plagal second mode," or even as using the "plagal second scale." I hear this often, from a lot of people - both students here at HCHC, and even some members on the Greek side of the forum.
For instance, I once asked in a topic on the Greek side if there was music for the Stichologia of Vespers in second mode hard chromatic (to match the score composed by Papa Ephraim in English, which can be found
here), and a member responded to me by asking (rhetorically - at least according to him) - "is there a difference between second mode hard chromatic and plagal second?" (or something to that effect, implying that I could simply substitute the music for the plagal second Stichologia of Vespers instead of searching for a score in second mode hard chromatic.)
This is an extremely problematic view, though, for there is indeed a huge difference between second mode hard chromatic and plagal second mode, and that difference is, of course, the theseis - formulae - that comprise the mode. For this reason, I find it far preferable to define modes in terms of both the formulae
and the scales - since many, many modes use more than one scale (e.g. fourth mode). This prevents the erroneous view of conflating different modes, simply because they happen to utilize the same intervals.
I realize, Mr. Nassis, that in all likelihood you are not advocating a conflation of these modes, but the idea did seem relevant to this topic.
Perhaps the distinction will be helpful to some - and it makes far more theoretical sense for me to explain to a student that, "second mode has several variants, one of which utilizes the hard chromatic scale and one of which utilizes the soft chromatic," than to say, "some of the hymns in the second mode section of the Anastasimatarion are actually in plagal second mode".
-Gabriel