I kown that Sanguinius is always represented as fair-haired, but this one is a comission and he wanted it dark-haired. He says that in "Horus rising" Sanguinius is discribed as dark-haired.
Which is a great reason for a "5" rating, isn't it? :P Anyway, I'd love to see more details on how the conversion was done. The paintjob could have stood more attention to detail on things like the purity seals, which look a bit ham-fisted. The leopard head is also a wee bit... gormless-looking, if you know what I mean? But that's just detail. This is a very competent piece of work. With a little more time spent on painting it could easily have been a "9".