Your average road bike in your price range will weigh in at 7 - 8Kgs, and the average dual MTB 10 - 12Kgs.
Not a huge difference for the average rider. The best advice given by many is take your time, look, ask questions, and try them out.
I'm sure personal comfort and feel will get you the right bike for your needs.
Life is too short to bother with idiots