In my opinion Engineer class is really not suitable for Dragon Ball Online.A Saiyan with guns?Why would they use guns when they're a warrior race fighting with their own abilities.Many games have these gunners and it doesn't make game better.
First off, they're humans. Just because they have Saiyan blood doesn't mean they have to be a Saiyan "elite" like the rest of the recorded Saiyans. They're humans before they are Saiyans, and they definitely don't live by the ways of the Saiyans. (If they did, they'd be the only race on Earth.)
And secondly, Engineer was originally going to be in the game using Bulma as a basis for the class. What does that say about the Engineer class? That they aren't Warriors, like Goku, Vegeta, and all the other saiyans, but ones that makes complex designs to help their group, like Bulma. This is tying the human up to their human side, not the saiyan side.
Did I mention the fact that humans don't have to live like brutes like all other saiyans did? Look at Gohan.