hi cosmo-torun, Our new observational method of measuring inhomogeneity in the metric, and the initial results, are now public: http://arxiv.org/abs/1410.1687 This will make it even harder to explain the FLRW interpretation of observations to people just learning standard FLRW cosmology - what do "comoving coordinates" mean physically when one of the best known "comoving" tracers - the baryonic acoustic oscillation peak at about 105 Mpc/h - is an environmentally dependent length scale? I have been telling almost every monograph or cosmology class at TCfA since I arrived in Torun that a scale as large as 100 Mpc/h should definitely be considered as comoving. Now we know that that's an oversimplification. pozdr Boud