He Is Legend is pretty good...they do that whole smart-ass, southern-rock take on hardcore - like a slightly less shitty Everytime I Die - only I guess on their new album they did a lot more singing? "I Am Hollywood" was an interesting album, but I stopped following them after that.
Killswitch is...uhm...breakdowns and yelling, then whiny singing parts.
Chimera I have not heard, but they're on Ferret Records which usually means mediocre-to-decent range metalcore.
Honestly, if you like DragonForce, this probably wouldn't be that bad a show, but if they're not headlining (usually, this is what it means when they say "direct support - it's nicer than saying 'opening band' but I could be wrong) this it could be anywhere from a 25-40 minutes in set time, depending on the venue. If ticket prices aren't too expensive, I'd say give it a shot. I don't care much for KSE, but I know they put on a pretty good show.