Speed boosts are true, they were in some video, I hope someone else can link them because I can't remember which.
OT: Engineers are the most "supporty" class to me, operatives go off and do their objectives in little operative squads to benefit the whole team shooting people they see along the way. The soldiers are busy at the front lines blowing things up and shooting people between him and his objective, medics will be busy healing up at the front lines and laying down suppressive fire while healing. Engineers to me are more of a non confrontation class that fortifies and defends, placing mines, repairing command posts, and deploying turrets. None of which require personally defeating many enemies besides the occasional operative trying to sabotage your command posts.
Even though your class doesn't "strictly define" your role, that's just how I see it.
Ah, I see. That is how I saw about it, too. And, don't forget about, um, what was it called?----hacking(?)/disarming(?), other people's----Soldier and Operative's device stuff, too? So, they can also go to the enemy's side (and shoot people on the way, lol) to get those hacking?/disarming? objectives or whatever.
BTW, I voted for ALL of the classes. ^_^ They all have their roles.