I've also been in search of music similar to SX, but have had only limited success. Most of the suggestions I get are all neo-classical; this is fine, but but I like SX's blend of progressive and hard rock (at times) with the neo-classical elements. My favorite SX albums are V, Twilight in Olympus, and Damnation Game, though that is definitely not to say I don't like the others.
As far as what I've found so far that I like: I second (third) Myrath's first album, as well as Redemption. You may want to to check out Pathosray's first album as well--It's much more thrashy, but if you like good, technical hard rock you may like it. I really enjoy the guitar riffs in some of the works of Pagan's Mind, but you have to get past the vocals.
I have to agree with Suspyre being "grooveless typical power metal," though. There are some great musical bits, but their songs are too long and start to sound the same. Their sax player is also flat as hell.
I'm going to check out the rest of the bands mentioned here in hopes that they're not all just 90-100% neo-classical.