As far as I recall, the minhag in all Ashkenaz shuls which I have ever attended, was not to answer Baruch-Hu-Uvaruch-Shmo to the name of Hashem in the Bracha which is said before the Haftorah, but in the brachos which are said after the Haftorah, the congregation does answer Baruch-Hu-Uvaruch-Shmo.
Does anyone know of a source/reason for this?