Wow if SX has really fixed their sound issues, that's definitely something. Whenever I've seen them the sound has been really poor and you can rarely hear the keys. I think someone here did indicate that the sound was kind of bad at their show - one of the early ones, maybe Pennsylvania. If they've improved it for most of the other shows, good for them.
I didn't see DT on this tour either but I've never had a problem where I could only hear Petrucci. I usually think JM could be turned up, but even feel like that was better for TA and Distance Over Time tours. And I can always hear Jordan and Mike.