You really can't have too much surface agitation... if it doesn't bother the fish, it's not too much. That said, the two filters should give you adequate surface agitation. I have a spray bar on my 150g coming off my fluval 405. I keep it right below the surface so that it makes ripples across the top. Never had any issues.
"What, exactly, is the internet? Basically it is a global network exchanging digitized data in such a way that any computer, anywhere, that is equipped with a device called a 'modem', can make a noise like a duck choking on a kazoo." - Dave Barry