I really can't answer your question about the power of the lights, because I do not know. I use them rather infrequently, but they seem to get the job done. The 6 PIAAs on the grille are really out of boredom, not necessity. They were on sale for $50.00/pair, so I couldn't resist. The lights on the roof are what the installation team at GOBI put on there when we switched from the Stealth rack to the full size one.
As far as the bracket difference goes, the rack does have a little flex to it, so the 4" brackets with the existing roof bars do add a little bit of structural integrity. Again, you would have to put some serious weight on the roof to see the difference.
There are some photos on the site with a bunch of us on Paul's rack, and some others on Blake's rack in NE, I think. I'm sure they can be found with some digging. With 5 or 6 men on the rack, it flexes a little bit, but it had to be over 1000lbs.
You can always e-mail me with questions at
adam@gobiracks.com if you'd like.