I am running rootbox 2.9 with dori 7.3 and have to say, it is by far the best and smoothest setup I have run on this phone! And battery is very good! I am running the performance profile and overclocked to 1.5ghz and I still get 3 hours on screen and 20h battery. Love it.
And I think it is sad to loose GM but dori is much more committed anyway, and very knowledgeable in any case, the only reason why he doesn't differ more from siyah is because GM doesn't want to release some of his source code, but this might change with the last siyah release, so dori can work his magic even more...