It seems to me that it's the prog fans who don't quite appreciate their heavier work. I can understand that, but looking at it from a pure metal perspective, they are very well received as of late. And I still think they offer something for everyone.
I am sure they will put on a great show nonetheless. Give them time, like Opeth and PoS, they will go back to their roots eventually.
I'd say I'm 65% metal and 35% prog and definitely lean strongly toward the first five albums. I enjoy parts of the Odyssey but beyond Inferno, Accolade II, King of Terrors, and the title track, I get bored quickly. I guess what makes SX so special to me is the captivating beauty of their melodies/themes and the grandiose nature of their songs in general.
It seems like they're still trying to figure out how to incorporate higher levels of heaviness into their music without it being at the expense of what already makes them great and the results are just not that thrilling to many, including myself since so much of it nearly comes off like decent-but-not-great b-sides.
I just miss the "WOW!!!" factor I used to get each time I listened to a SX album for the first time. I think they still have it in them but for it to occur, they're gonna have to truly want to make an album of that caliber without feeling some need to be heavy as a first priority and just realize "hey, we can make an awesome album and the moments where heaviness is needed will become apparent during the extensive writing/arranging process."