Well, here is what one can achieve from the light polluted outer suburbs of Sydney using a Televue NP127is refractor, a cooled EOS 50D, and Astronomik 12-nm H alpha (red channel) and OIII (green channel) filters. The blue channel in these RGB images was extracted from exposures using a Lumicon dark sky filter. I have always been very pleased with this filter - it can increase the exposure times by a factor of 2 beyond the limit when sky glow begins to reduce the signal-to-noise ratio. Even so, I would prefer to record the blue channel data out in the country.
The images in my flickr set were downsized by 75% in resolution to help keep the required internet bandwidth and usage under control.
http://www.flickr.com/photos/mlparkinson/6992249065/