Hi Colin
Great cluster but you are missing the star colour. If you want colour in your image, after calibration And registration you need to debayer the subs using the debayer process. You should be able to get a range of star colours even if you have selected the RAW monochrome setting in Maxim.
There is a good DSLR workflow tutorial here
http://pixinsight.com/forum/index.php?topic=2570.0