Galaxies are humbling experiences. First there is the grandeur of them. There's nothing like a galaxy to make you feel small and insignificant. Then there's the processing.  It took seven tries until I got a result I was happy with but I finally feel like I did some justice to the data.

The major challenge is managing dynamic range. The core and nebulae are bright but the fringes are dim. Normal stretching methods were not able to work for me. I tried the Generalized Hyperbolic Stretch script but I still wasn't able to cope with the dynamic range. That probably says more about me than the script. I suspect in more capable hands it would be up to the task, but I couldn't find a way to do it. Instead I turned to a technique shown at a club meeting by @Randy Lindstrom. This worked out perfectly for this galaxy and also served to help me get the color saturation where I wanted. Essentially it involves alternating high range expansion in HT with a gentle midtone stretch (0.25). Essentially this keeps compressing the high end of the histogram back down toward the center and keeps you from clipping anything that didn't start out clipped. It also includes a color saturation step that helps boost color. I toned down the color boost from Randy's example. On this image it felt unnatural but the idea really does help keep color while stretching. UPDATE: In revision B I was able to do the stretch entirely in GHS.

I also ended up doing a background neutralization/color calibration rather than a photometric color calibration step because PCC just didn't do a good job on the galaxy. It left things looking reddish and a bit muddy. The old school BN/CC steps saved the day for this one.

Here was the workflow:

H:
pixelmath h - r*scale

R:
pixelmath r+(h-med(h))*scale. (masked with copy of H that was stretched and manipulated to increase contrast)

RGB
channel combination
dynamic crop
DBE
blurxterminator
GHS
starxterminator
noisexterminator
GHS (final stretch)
HDRMT (heavy mask)
LHE (heavy mask)
MLT (sharpening, heavy mask)
pixel math in stars (screen)

stars:
GHS (minor inverted stretch)
unsharp mask (very mild sharpening)

Original Version:
RGB:
channel combination
dynamic crop
deconvolution
DBE
MLT noise reduction
background neutralization
color calibration
HT high range expansion (1.3)
color saturation
HT high range expansion (1.2)
HT midtown stretch (.25)
alternated high range expansion/midtone stretch until the image was where I wanted
HDR multiscale transform
LHE
NRGBCombination in H
Curves (slight color boost)
EZ Star Reduction script
MLT Sharpening
in photoshop:
color range selection on galaxy core
hue adjustment to bring the core more toward yellow from the salmon it had become
add a bit of vibrance in adobe camera raw filter
and then back in PI
SCNR to gett some green tint out of the core

While M106 is the focus of the image I decided to crop to leave in a lot of the nearby galaxies. I was back and forth on this until the last minute but ultimately decided to leave the neighbors in.

I want to thank John Kasianowicz and Christoph Bertsch for making this opportunity available to me. The chance to use great equipment in a dark sky is a joy!