I posted a screen grab of the mixing tool because it showed where the speakers were. But here's a better graphic:
The initial consumer version of DTS:X (there is a separate theatrical version) will be limited to 7.1.4 (no Wides, like Atmos has). Front height speakers will give you a tall soundstage up front, but not the impression of sound overhead (the way DTS:X and Atmos want). If you're limited to placing height speakers high up on the walls (rather than the ceiling), then you'd be better off placing them high up along your sides instead of up front. This way, at least height information will image above you.