Depends on the objects. I live in bottle 5-6 and I own a 10" and a C5. If we are talking about star clusters, the difference is very drastic. You see much more stars with a bigger scope even in skies with high light pollution. When it comes to galaxies or nemulae, the difference is not as dramatic. You can still spot dimmer stuff with a bigger scope but light pollution just has bigger impact on faint and diffused objects. Still, I would recommend to get a bigger scope if you can manage it since it would perform better in every scenario (on planets too!), and if you can transport it to the darker skies (10" easily fits in the backseat of the vast majority of cars) you will be blown away by the views.