Go with the RaceDeck, you won't regret it. RaceDeck REVolution is thicker and has more locking mechanisms. It is geared more towards commercial installations. It won't hurt to put the REVolution in a home garage, but it is way overkill. The REVolution has only been out a couple months so everything you read here about RaceDeck is based on the standard RaceDeck not the REVolution.
I have never priced the metal RaceDeck, but I think it is considerably more expensive. As far as I know the metal really is just designed for small accent areas, not to be used as a complete floor. Most likely it will scratch and dent worse than the plastic.
I was skeptical of the plastic tile based on my experience with a cheap chinese made tile from Sam's Club. RaceDeck is far better quality. Just call them they will send samples, once you see them it will be clear RaceDeck is the right choice.