Interesting! Tip o' the hat to you Eddie for giving it a shot. I guess you now know that answer... Galaxies are wide band spectra targets, similar to clusters. If you're keen to use narrowband on galaxies, stick with Ha to emphasise the HII regions in a traditional RGB data set. Chris Schur did a presentation at AIC2007 on the topic which maybe of interest to you.
http://www.schursastrophotography.co...nt/AIC2007.ppt
All this aside, don't waste the data. You can always do some synthetic channel work to produce a psuedo RGB. It would probably turn out a stunner. Your stellar profiles are as tight as I've seen from the GSO RC8, undoubtedly due to the narrowband filters reducing bloat.
Cheers