I feel somewhat unsure in this particular case regarding the marathon thing...
I remember when DT following SFaM announced that they would have a 40 min-track and I just refused to even listen to it.
After spending some years with Spcok's Beard and Transatlantic I feel somewhat more comfortable with the long ones.
Had I preferred an SW disc with more songs -probably.
But here is how I think to console myself;
-I loved MF but the concept thing can get a bit too much at time, but at the same time I am a sucker for the dramas and longer stories where you in fact get a chance to feel what the characters are feeling and get to know them a bit better. So since I wouldn't like them to do MF again, but I still love the concept albums (even though I always think I won't) I will consider the llong song on TGE like a mini-concept album, and the rest of the album a regular one.
Now, if it is considered a mini concept album, then it would be just like listening to MF (but shorter) in which case I am perfectly fine with it being "many songs joint together", which is what a concept album really is.
In my book you could get away with the whole verse, chorus, verse, chorus, solo chorus-routine for about up to let us say ten minutes, given that the instrumental sections are awesome. But if you are gonna go longer than that it requires songs within the song (but some melodies or rhythms etc that keep popping up are still cool).
That was a long way of saying that to me it is not negative with the long one sounding like it is made up of several shorter songs crammed together -just think of it as a concept album but that you can't skip through the tracks.