In this paper we give new insights into quantitative microwave tomography with robust Huber regularizer and Gauss-Newton optimization. Firstly, we validate this approach for the first time on real electromagnetic measurements. Secondly, we extend the framework with a modified Huber function, which behaves like TV regularization. This is interesting for reconstructing piece-wise constant permittivities that appear in non-destructive testing of installations and other man-made objects.