This is incredible work. I've written similar abstractions for my former startup (http://bubb.li/ - it'll take a while to load) which abstracted a 3D rendering engine across CSS3D, WebGL, and Flash. Unfortunately, when we launched the only platform stable enough for CSS3D were Safari & Mobile Safari and some Android (they also couldn't run any of the other aforementioned technologies at the time).
The primary issues are touch handling and clipping. The safari team nailed clipping (or they just relied on the GPU to do it for you) and touch handling has always been a little bit hit or miss, fortunately not huge for our requirements (although I did end up writing my own raycasting to compensate in some unreleased things). Chrome has been somewhat of an utter disaster with clipping and based on the current demo, still is (things flicker in and out randomly). They've come a long way (Android Chrome was locked around v18 or so for a while which was completely unusable for this sort of thing), but the fact that Chrome supports both real GPU accelerated and acceleration in software appears to have somewhat muddled their implementation.
The primary issues are touch handling and clipping. The safari team nailed clipping (or they just relied on the GPU to do it for you) and touch handling has always been a little bit hit or miss, fortunately not huge for our requirements (although I did end up writing my own raycasting to compensate in some unreleased things). Chrome has been somewhat of an utter disaster with clipping and based on the current demo, still is (things flicker in and out randomly). They've come a long way (Android Chrome was locked around v18 or so for a while which was completely unusable for this sort of thing), but the fact that Chrome supports both real GPU accelerated and acceleration in software appears to have somewhat muddled their implementation.