ooooohhh I see how this is gonna turn out, I'll be the only one that installs signs with 2x4 backers, yep seen this before. Well i'm not! and for the record we use treated lumber not interior studs ANd on accasion been know to use 2x6!
As far as the L clips what are you talking about? Im sure this sign was flush mounted and those were used to "support" the sign while it was being secured to the wall.
I do respect your methods and it is something to think about. Another thing for you to consider is all signs pass inspections here when using these boards. When I started working for the man 25 years ago thats they way I was taught and to this day it is the norm here. I am sure under certain situations it would call for aluminum plates if the sign was an extremely heavy structure, but I damn sure wouldnt hang something that heavy on some crappy a$$ drivit, which I despise drivit.
Everyone has their own way of installs and to date we have never had a set of channel letters or box fall off a wall, so to sum it up whether our methods are looked at not as superior as yours, they have not failed yet. Now I have seen people use big *** washers and nuts behind raceways and that to me is very uncalled for.