Sure have you don't want to go to large on the screen size (23" max) I'd say, as the hinges start to buckle and bend. Other than that it's a quality screen arm.
I couldn't possibly tell you anything about that particular panel, it must be a "weight thing" if Dell says it'll take it then I'd take there word for it. You always have the warranty and RMA behind you should anything go wrong.
If they say yours is within their spec then it should be fine, Contact them and ask them what you asked us and get their name and everything. If it goes tits up then they should be liable for it. Unless they try blaming you for it.