Thank you for the awesome and encouraging feedback guys...
Kevin and Brent, my 40D is not cooled, it is only astro modded. When the 30 minute subs finish the sensor temperature was reported as 25 - 26 degrees... and yes there was a lot of noise. There is something that I did discover recently... If you open the CR2 raw files in photoshop, CS4 is my version... the RAW decoder plugin does a very good job at removing just the noise. and I use CS4 raw plugin to convert all of the CR2 files to 16 bit TIFF. Once converted I created a "Action Plan" in photoshop to copy the Red Channel to Green and Blue channels and sharpen the subs using Unsharp mask set at 2.5 pixels and 35%, then save it. This is for the HAplha subs since red channel is the only one that has data, the other channels are just black with nothing by noise... by the time this procedure get done the sub is noise free. The Color subs are treated the same except the RGB channels are left as is.
The Grayscale converted TIFF subs can be dark subtracted, but I imagine you would have to do the same action plan on the darks or you'll be subtracting noise that isn't there anymore...
I want to note here that I didn't dark subtract or apply flats to this image subs... I didn't see the need to dark subtract since like I said the subs were very noise free and I just cropped out the vignetting.
So Brent and Kevin, I think you'll find that going over 10 minutes is quite safe and possible, but only through narrowband filters I suspect, at my location anything without a NB filter will washout within 10 minutes too.
Brent and Raymo I still don't think I belong with the big boys yet, not after seeing some of the gold they are posting.
The subs were then stacked in Nebulosity 3 and the end result was slightly adjusted in photoshop using curves... I didn't adjust it much, I didn't need to, the nebula was already smooth, detailed and bright.
I'm working on the Orion Nebula now but this time I will apply flat mapping... but I don't think I'll need to do any darks... I already did 4 x 30 minute halpha subs on it and the above procedure worked out exactly the same, very noise free. I'll do an experiment by capturing subs in Ha, OIII and Hbeta... then Combine them as HaOIIIHb (RGB), should be close to true color but with Narrowband detail... I know it says online that HBeta is not intended for photography but I'm thinking, why not, Its basically Blue with out the spill into green, like OIII is closer to green but with out the spill, like Halpha is Red etc... Only experimenting will show if this works... If not then I'll spend a night or 2 capturing SII and make a Hubble Palette image and a NB Luminance mapped RGB.
Cam, thanks for the tip with HaRGB processing, will definitely have a go at it... oh and that beer you claim I deserve, I'll remind you at the next IISAC...
.. but that feedback is great, since that make me feel like I achieved pictures that are an improvement over my last ones...
