I'm glad you kept the 7D and are out using it. Those samples are great.
A note on diffraction... I've tested diffraction on 35mm film, my old 20D, and my 50D, and I saw the same result. Worries about diffraction are somewhat overblown. I'm OK down to f/16 on all of them. Yes, when you conduct a test and compare the results side-by-side you see the image degrade some from, say, f/5.6 as you stop down to f/16, but it isn't bad really. The results are quite usable in my opinion. When you do landscapes and you need the DOF, don't be afraid to stop down, don't worry about diffraction too much. But it doesn't hurt to vary your aperture either. It won't cost you anything but a few more moments, enjoying a scene you find worthy.
On noise reduction, I've had great luck with CS5 (in ACR) and Noise Ninja (rarely using both, mostly using CS5 now). I've heard great things about Topaz DeNoise too. Glad it works for you.
As I said in your other thread, I think digital becomes more demanding in general as the pixels get smaller, so we have a bigger learning curve.