[NTG-context] relative scaling for fonts

Hi there, I'm using XeTeX one of the features that I miss at most from XeLaTeX (from fontspec), is the possibility to set automatically the scaling of fonts so that they match the lowercase or uppercase letters of the roman font. I wonder whether there is something similar for ConTeXt. By the way, the ConTeXt uses in my view, the wrong XeTeX way to set the interlinear space, since it seems that \XeTeXuseglyphmetrics is set to 0. Probably I should be missing something, but if \XeTeXuseglyphmetrics is not set to 1, ConTeXt will set the interlinear space not by itself, but following the glyph metrics and in some fonts the font height. I guess it would be better to use \XeTeXuseglyphmetrics=1. Best, Pablo