So after I got a stable version of Eyez (iOS) up in the App Store, I started integrating all the new changes into the WP8 version. And today, WP version 0.9.0.7 has finally become available!
From this version on, Eyez is a native WP8 app, and has the new playable character Hooded Girl that is available in the iOS version. Among all the tweaks, one big improvement is that the jump button control now works more responsively. I am also keeping the last WP7 version (V0.9.0.4) available in the WP Store, just in case some WP7 users still need it.