Glass body Pros:
Won't rust
Won't rust
Won't rust
I guess that's the only one I can think of.
Wait just got another, the cost is less than the steel body.
Cons
Devaluation? absolutely
Total custom build meaning you as the builder have to figure out many hole locations and mounting solutions for just about everything. Fitment of parts takes much more time. You almost always find stuff you should have trimmed, sanded or changed prior to paint but you already painted it.
Steel body Pros
Steel body holds value (until it rust)
Mounting locations are laid out for most things already.
Are you welding it together yourself? WH can ship it usually within a day or two.
Cons
Gona cost you for body and paint much more than most people expect.
It will eventually rust.
Good luck with the project let us know if we can help.
Jim