First batch of listening and feedback:

Meltdowner: I generally quite like your suggestions in these polls, same here. Calibre 35 has a nice retro sound with a modern vibe, but something is lacking to be really captivating to my ears. Brother and Sister's Magick and Mystic has indeed those magic and mystic qualities, rather dreamy and spacey (a bit Gong-like by moments); nice, but not the most original. Bando do Casaco, I think I prefer this one, it has something discomforting and at the same time it is fascinatingly beautiful, a pity that it is so short.

The Dark Elf: Wow, there's some tremendously good playing going on in your selections! Leo Kottke's piece is beautiful and captivating. The playing of Rodrigo and Gabriela is stunning and nice to watch, but the song itself is a bit disappointing to me. Musically speaking I prefer Michael Hegdes over R&G, here. The energitc punk-folk (or whatever) from The Devil in the Kitchen is a great listen too, but from all these I prefer Leo Kottke.

TCat: French TV have come by in several threads recently and every time I quite like what I hear,. This one too, but I also have the impression that there is a bit too much going on in just one song... hesitating... The Jon Hassell & Bluescreen piece (nice cover art!) is very nice and groovy, but I'm not sure where it is going. Scott Cossu, Yes, this could be played in a restaurant without disturbing the customers, but musically speaking it is a very pleasant listen; there is more going on than a first impression could suggest. With Yello I have always had the same problem: when I hear a song I find it great, but when I listen then to the whole album I am disappointed - too much of the same. I prefer Ciel ouvert, Stalakdrama is bit too grotesque for me, Sonically speaking they are both indeed very impressive, but music-wise I am a lot less impressed. I prefer one of the other three but don't know which one yet...

Snicolette: Well, sorry but you're not winning me over with the harp pieces; especially as solo instrument it doesn't captivate me. I like some of Stivell's folk rock work (had an album once on cassette, which was very good), but this one leaves me cold. Frankfurter's piece is more interesting though and Mason Williams & Deborah Henson's Classical Gas even more (although I prefer the Glen Campbell version by far). Your order of presentation is my order of preference: the best one for the last, Tom Kelly's God and the Flatlanders. I like how this one evolves from a more classical overture into a more layered and rock tinged track, without losing those classical qualities. Wished it was longer...

FatherChristmas: I'm not much into djent-filled heavy prog or prog metal, but Cloud-Burst is not unpleasant. Nice interplay between instruments with some straightforward but nevertheless captivating riffs and a nice closer. Super-silly clip though ;)

Lewian: Salaryman, didn't know them so this is a nice discovery. You hear that a good production is important for this kind of music. Great track, good groove, wonderful interplay and not that monotonous to my ears (makes me think a bit of Sonar...). I think I prefer them over Startling Insects' Underworld which is very good too, but I find it less captivating than Salaryman. Regarding Joe Jackson, back in the 80s I listened to several of his albums but always turned back to Night and Day, the only one that really convinced me (and that I have) - Nocturne won't change that.

jamesbaldwin: You bring us on a nice trip around the Mediterranean. With Gilad Atzmon Klezmer is brought back to the Balkan but not without picking up some jazz underway. Very nice listen! Roxanne's Passion Tango is quite good too, but rather classic in it's approach (I started to like tango thanks to Carlos Saura's tango-films...). I very much like the more experimental Cassiber with Chor der Gefangenen. Unfortunately, Stormy Six is not available to me and I couldn't find an alternative. My choice would be between Gilad Atzmon and Cassiber, probably depends of the mood of the moment.

Cristi: (some of the songs are too long re the criteria defined in the OP...) Nice to discover some Roumanian music, with Basorelief, Adrian Enescu (he was also in an earlier poll!) and Post Scriptum. The funky side of Adrian Enescu is not what I prefer, and Post Scriptum seem to be more a show-case piece than a song, but it is a nice performance. Phoenix has a nice festive quality, but my preference goes to the fusion of Basorelief.
You know that prog metal is not my stuff: Cromwell has some good moments, but Walking Across Jupiter they can walk without me.