@gavinturner: Yes I saw that in your build diary! I've spent some time checking how you went as I'm pretty much going for the same finish
So to try to avoid that I've gone with very thin coats of dye (hence the 6x applications), and I've tried to leave at least 4 hrs between applications to try and let the timbermate dry again between coats. But you can feel the wide grain valleys you mention...
Did you manage to get it perfectly flat with the clear coats at the end or do you still have these?
Cheers!
Fred