When I got my ASI224MC planetary camera, I did a bit of work testing the performance of it compared to my Canon 700D (which I picked up 2nd hand pretty cheap). You can see some of the tests I did using my 6" SCT on the CN website
here,
here and
here. It performs very well when the seeing is good and wind levels are low. Because the LiveView functionality (essential for planetary imaging) is fixed at 1/30 sec shutter speed, any vibrations on your scope cause by the wind will blur the image, and strong jetstreams will also reduce the quality more than the dedicated planetary cameras.
In terms of focal ratio, the general rule is to image the planets with f/num = 5x the pixel size of your camera. My Canon 700D has a pixel size of 4.3 microns, so the "best" focal ratio was f21.5, so a 2x Barlow on my f/10 SCT was ideal.
If you are new to planetary imaging, you
really should watch
these videos, they will tell you a lot. Note that Steve recommends the NexImage 5 as the camera of choice, these were done before the ASI224MC came out.
Hope this helps,
Andrew