Yeah! Long live rental telescope data!
A good experiment Craig. I went down the same road two years ago producing a similar composite to what you've portrayed using a long focal length for luminance and fast wide field data for RGB. You'll find a few examples on my site such as M27 RGB, M83 and my first attempt the Cat's Paw Neb.
Its not too difficult to match up, but you guys trying to match the rich contrasty nature of Ha data can present its problems. You'll find you will obtain success or at least a better result if the approach is iterative. i.e. don't go straight for an LRGB blend, but an LLRGB. Downsizing the high resolution luminance to match the RGB to create superRGB layer, then upscaling it again to match the original luminance will assist. It gets harder to match as the differences between the two focal lengths increase. If the two data sets are at a similar focal length, the better the result.
I've since ceased experiments to progress the technique as I found I began to cross the line with what I felt was ethical. PS is an extremely powerful tool in the right hands - when you start to get out the paint brush to manipulate star colours such as diffraction spikes and other features I felt I was taking it too far. Each to their own I guess. I just wasn't happy about it. Nothing can compare to capturing RGB data on the same instrument the luminance was acquired.
I like what you've put together. Perhaps a little too saturated, but Ha blends take sometime to get right. I still struggle with them. Keep at it if this is the desired path you're keen to investigate. Also, make sure you're not downloading the precalibrated light frames from Lightbuckets - make sure you download the RAW FITS and perform calibration manually with the correct Flat based on PA.
Cheers