For what it's worth, a few years back I interned at a boutique agency in Los Angeles. We never rejected a submission based on the wrong type of Courier. We wanted to see talent and commercial viability, and if it was going to make the agency money, I'm fairly sure they would have accepted something written with crayon on a napkin (but don't do that).
I should mention, though, that the agent I worked with was probably the type who saw Transformers this past weekend and declared it a masterpiece of screenwriting.