I finally got around to buying some replacement brushes for my Sonicare HX6731/02 Atlas 7000+ brush. One thing that has always bugged me about this sort of product is the cost of the replacements. So, being quite expensive, I've put off buying these until it was absolutely necessary, and quite clearly, it really was necessary. I now remember what a superb job this brush can do. My mouth feels fresh and clean again.
I have also not experienced these brush heads breaking. Not quite sure how that could be done under normal usage?!
My lesson here: 6 months is probably too long to wait when the manufacturer recommends 3 months!