It serves me well enough to hold a D70 + Tamron 70-300 LD, and I figure it can hold any lens up to a 80-200 f/2.8. Any extra weight ought to make it unstable and jerky. The locking mechanisms are ok as far as gripping is concerned, but the rubber foot tends to make it slip (therefore the Slik...
Cons
It serves me well enough to hold a D70 + Tamron 70-300 LD, and I figure it can hold any lens up to a 80-200 f/2.8; Any extra weight ought to make it unstable and jerky