This is probably the least favourite of my "white" M600s. Its just too white. I worry about staining it so I use very safe inks with it.
The only 18K full rhodium plated nib I own. It came with my M625 Red pen and it is quite a nice writer for a boring medium nib.
Its been almost two years since I last used this ink and my thoughts have not really changed. It is still a nice shade of red-brown that does not shade.