If BCSL is the end of "classic DT era" so I'm glad that "classic DT era" is over.
Amen. The Mangini-era, the Astonishing aside, which caused me great anguish, has been one of the best things to happen to this band's output.
Also, I don't know why BCSL would be the end of the alleged classic DT era. Their albums are different enough that one could reasonably say there is no classic era. Seems like an arbitrary point unless MP is somehow required to define the classic era.
To me, the classic era of WDaDU-Octavarium is a band who did put out a different album every time, where there was little regard for genre. DT was a fusion band, not just a progressive metal band. They fused metal, with progressive rock, a touch of jazz, with some classical influence, and blended it in such a way that it was both complex and catchy/memorable, something most bands struggle to do consistently. DT did it for about 8 albums straight. ToT was a sort of departure from this, but only that they wanted to make a heavier album than they had up til that point, but the concept was still the same. Octavarium had songs that were more straightforward like TALW or IWBY but weren't still focused on "this is the [insert genre] song" and the other songs continued the DT tradition described above.
Enter Systematic Chaos. Now this album did some things similar to Octavarium (lifting direct influences from other bands on certain tracks) but this time, it was all about balls and chunk, and trying to appeal to the broader metal audience (whereas ToT was just a desire to make a heavier album) while making sure the music still appealed to their core fan base. BC&SL continued this trend to an extent, but I think it was a better album, since to me SC loses momentum after TDEN, and they were less concerned about the balls and chunk overall, bringing back lighter playing and proggier compositions, particularly on the back half of the album.
Since then, the albums have been either an attempt at former glories, or doing something so outside the box for the band it fell short of even the biggest Mangini-era fans liking it (The Astonishing) and between all 4 albums with MM, while the production is different on each album, the core sound of the band is the same. There is little to no progression in their general sound since SC, other than MM replacing MP before ADTOE. DoT could have been written in 2011, and ADTOE could have been written in 2018. Minus lineup changes, I can't say SDoIT or ToT could have been written in 1992. I don't even think Octavarium (the song) could have been written in the 90s. They had to grow and evolve to be able to, or want to, write the music on those albums.