Yo Slim,
I did my interior with duplicolor and my exterior with Durabak. The duplicolor is decent, but is far inferior to the durabak. My durabak has been on the outside for a year and is the toughest stuff I've ever seen. I used the textured but wish i had gone for the smooth.
The inside of the truck is def. louder than when I had carpet, but I would still recommend doing this as long as you don't mind some engine noise. If you've already removed the carpet its a no brainer.
You'll get what you pay for with the products, and prep truly is everything. Prep took longer than application for me. Sand really good and clean with the correct solvent for the stuff you're applying. Acetone for duplicolor, xylene for the durabak. I applied with the roller and it went on great. Not sure what solvent herc uses - never tried it.
I can't recommend that durabak enough. It's the toughest stuff I've ever seen.
Here's the link , it's only available online. Branches will fear you.