Curb Mount Vs Deck Mount

What i usually come across in my work is asphalt shingle roofs, 4 in 12 to 12 in 12 pitch.

Curb Mount Vs Deck Mount. Generally this box is comprised of 2×6, or larger, construction lumber set on edge and attached to the roof deck. One of these skylights is just under the edge of a large tree's crown.

Half Round Skylight Roof Systems, Roof Deck Mount or Curb ...
Half Round Skylight Roof Systems, Roof Deck Mount or Curb ... from i.pinimg.com
Wasco curb mount or deck mount traditional domed units offer outstanding lighting and thermal performance in a versatile range of dome or pyramid styles. I will be replacing two existing flanged mount skylights. What makes them better than pcb or plate mount stabs?

One of these skylights is just under the edge of a large tree's crown.

Curb mounted skylights are the most common skylight type. Fixed units are also available as hurricane. I will be replacing two existing flanged mount skylights. But now i need to know other points of view on the subject.