I have some bad news chaps, after my first shave with the brush it has a cavity. I don't think I've caused it, it's only used with creams. I do face lather however not a masher and my other 4 brushes are fine. I've sent the photos to mark who would like me to send it to him to analyse.
Had my second shave with it today, I echo the other comments really. It whips up a lather like nobodies business (Dr Harris - Windsor) but for me it just doesn't have that soul. Very springy, which isn't always a bad thing but a more give would be nice. The handle is lovely but would love a bigger knot in it. As it was my first synthetic I found getting the water balance a little tricky so perhaps it's better suited to bowl lathering.
On closer inspection it doesn't appear as though the hairs are missing or broken just to one side. Very odd. I will try and upload some pictures here later.