I know it will add some extra weight. Right now it weighs 180G so steel cover will make it around 200G. One would hardly feel any difference

You don't have girlish hands that will feel any kind of strain while holding just a 200G gadget.

Afterall there are handsets which are bulkier than N900 and their perfomance is no match compared to N900. Take the example of Omni HD2