Man this subject comes up a lot!
In trying to determine "which one is better" it really helps to have a clear question like "better at what?"
OSC was originally developed for video applications. All other aspects of color sensors are compromises when compared to their mono counterparts. Since color video is rarely a requirement in astronomy (even the best high res planetary imagers use filter wheels with mono cameras) there aren't any technical reasons to use a OSC, except cost at first look, but I believe that is a fallacy. What does a mono sensor give you that a OSC can't?
Higher QE = more signal, reviewing the QE graphs and filter transmission curves tells the story.
Higher QE is the same as getting a bigger telescope with the same focal length with no added mass for the mount to handle. How is that ever a bad thing? What is the alternative? A bigger, faster OTA and a beefier mount to hold it? I think any cost savings of the OSC just got swallowed by the shipping cost of the new mount
The resolution thing is not a big deal if you have some freedom with focal length. Anyways you can think of OSC pixels as 2x2 blocks, hence your effective pixel size is 14.8 um (for the popular 7.4 um OSCs), and use this to calculate the correct sampling.
OSC astro images are not as easy to process as some mono frames, especially in urban conditions, where ironically most OSC are used?!? The effects of light pollution make flat fielding vital, but it's harder to do right in color land.
And of course the kicker is narrowband. Narrowband has the most bang for the buck in light polluted skies (again the irony) but check the QE of a OSC at 653 nm (HII wavelength), not pretty.
So IMHO if someone is interested in taking pretty pics of the brighter nebulae, a DSLR is way cheaper (what's my ancient 350D worth these days?), does an pretty good job, and easier to justify to your better half than an astro OSC.
EB