Intel seem to disagree with you. They rather write their driver the old way, and do not loose 5-10% of computing power. For people who would like to use Linux as a gaming platform, 5-10% loss in performance due to (avoidable?) layers of abstraction (i.e. John D. Carmack's "layers of crap") is quite much. The claim, that Gallium3D could cost maybe 5-10% of performance is from some VMware employee, in some Video I once watched on YouTube.