I have the fancier, ala cart, ARE commercial version.
Pros:
Easy to modify since it's metal
better locks/security
side flip windows offer awesome access
No issues with huge amounts of roof loads
cheaper than fiberglass
cons:
looks like a work truck
poor visibility (I got used to it and could care less now)
conductive (condensation issues if you sleep in it)
slider to cab is a horrible match and is almost worthless