I also love Labrie's unique voice, but for me, that's an exception, not the norm. I've also known a few people who were turned off from DT just by the vocals alone.
I'm willing to bet they're all too young to have lived through 80s rock vocals. LaBrie's type of voice wasn't even slightly atypical in the late 80s/early 90s mainstream hard rock/metal landscape and his performances on I&W and Awake are stellar. It's hard to imagine they could possibly have found a more appropriate singer at that time and I believe he was a large part of what lifted them up out of the little leagues, which is where they were with WDaDU, which was little more than a curiosity.
LaBrie's voice in the post-grunge, post New Wave Of American Heavy Metal landscape has ended up sounding like something of an anachronism, but I've always found it a bit sad that LaBrie sounded great singing some fairly metal songs on Awake but from The Glass Prison onwards DT seemed to lose the ability to tailor the writing of the vocals for heavier tracks to the singer they
had rather than some mythical singer that didn't exist. Sure, someone such as Robb Flynn might've suited a stock barked metal vocal such as Constant Motion way more than LaBrie, but there's no way that kind of singer would've sounded anything other than completely out of his depth attempting something such as Octavarium, which LaBrie is simply fantastic on.
Anyway, JSS's clearly a more than capable singer but I just don't get any sense of drama from his voice. I don't think his vocals will be the sticking point for the band the way the incessant falsetto on Flying Colours was for me, but if there's the same lack of vocal hooks on the rest of the material that the opening track suffered from then I don't imagine I'll be giving it much attention.