@ rooperi: I myself have lost immediately against the Larsen (b3). It was one of my first tournament games and I simply panicked. But I was both inexperienced AND I have some anxiety problems.
I have a friend who also won with the Grob, mind you.
But those openings are only as good as somebody has never seen them. A decent player just needs to spend an afternoon to prepare against each of them. So you are seriously risking to give away your white advantage for nothing.
cheers rooperi i have just started to play it and am finding it very good both as white and black,i think it is the best opening i have played . i have had some good win's over higher ranked opponents with it ,though i have also been well beaten sometimes as well but i think that was mostly down to mistakes by me and not the opening.thanks for the comment