Robert_Charlton - 8:23 am on Dec 7, 2010 (gmt 0)
redress this imbalance by linking back from the brand pages to the subcats pertinent to type of products the brand produces
It sounds like you understand link juice distribution. I can't see any problems, as long as you are careful not to create multiple urls for the same page.
Absolute urls are the safest to use under this situation.