Bringing the XUL UI up to date is an option, but will the XUL build automatically benefit from OMTC when it'll be fully enabled in the code, or it'll require some modifications? If responsiveness of the XUL UI will significantly improve - there won't be a need for Qt one, since XUL is naturally portable already. But right now it's a real pain to use (I'm testing it on N950). Constant freezing and unresponsive behavior are just bugging the whole experience. I'm not sure though if it's Harmattan's specific problem or not. I didn't test it on Nemo yet.