D. Koubaroulis: I was never taught syneptygmenos and I have never seen anything written about it in any book. The first time I heard of the name was by L. Angelopoulos' students who would count classical pieces in Tetrasemos (2+2) and would call that syneptygmenos. I had noticed the irregular chronos used for e.g. the Epinikios Hymn of St. Basil's Liturgy or the kratema of Theotoke Parthene by some psaltai but that's about it. My aim with this page is to clarify what syneptygmenos is and to provide recordings that demonstrate it.
G. K. Michalakis: Applied in quick Heirmologic and Kratima. The composition isn't in regular rhythm. When it is (example "Epinikos hymnos, Tin gar sin, Meg. Basileiou), we are dealing with diplous chronos. That is, the composition is such that we hear every thesis as a "double duration". We can apply syneptigmenos there as well, but one has to be a good and well-learned performer. In the Kratimas and the Heirmologics, Syneptigmenos is what gives some accentuated syllables slightly longer duration that others. One learns syneptigmenos by chanting while walking, and feeling the "alternating balancing motions " of the body. No syneptigmenos has been put on record by Iakovos, although it was chanted in the Patriarcheion.
As for the question concerning the syneptigmenos symbol in Boudouris' transcriptions of Exapostilarions with the added comment 'haplos' chronos, my opinion is that, in these few cases, he uses the symbol in the current, occidental use of 'cut time' = give every neume half its value without further extending or abbreviating the durations, which would give rise to syneptigmenos, which is what one should sing traditionally when the aforementioned symbol is indicated.
Many have tried and many 'try' to do syneptigmenos chronos. Panagiotidis does it decently, Taliadoros sometimes as well. Tsolakidis, of course, is the best I've heard. I don't know what Karas' definition is. If it is simply "cut time", = chant the thing at twice the tempo", then I certainly don't agree. I've never heard EBX do syneptigmenos (therefore, much less so as according to the Patriarcal definition).
[The kratema of the verses of Theotoke Parthene of P. Bereketis] is not trisimos but syneptigmenos which has been reduced to Trisimos by untraditionally-trained psaltis. More of GKM's views on syneptygmenos on his web home Psaltopedia.