This is all quite interesting. Today I had the experience for the first time where I really did feel the JPEG was superior to the RAW for a particular photograph. I spent a lot of time trying to "improve" the RAW version to be close to what I liked in the JPEG version. I'm not usually the "testing" type and I'm certainly not an authority on Aperture 3, but it has been interesting.
I keep coming back to the fact that what I want, personally, is the image that I think is good. I don't really care if it looks just exactly like life, though sometimes I do want it to. I want it to covey what I saw in my mind's eye. I think that sometimes I become so obsessed with zeroing in on how the image looks when I use the "loupe" - the magnifying glass" that is one of Aperture's tools, that I find myself worrying about whether or not it's too grainy or not...and I forget about the photograph as the image.
I don't know if anyone else can relate to this or not. What's interesting about this particular camera is how one can still get a worthy photo even at very high ISO speeds. I've tended to use Auto ISO and I can see that for some inside shots, that is not the wisest choice. So my X1 and I have a long way to go as I get to know her better. Yes, I do think of this camera as a her. I don't know why, but I do.
Here is a photo of my dog. I'm not suggesting that this is a work of art, but it's an example of the X1's jpeg taken f/2.8 @ 1/500th ISO 320 with an EV of -0.3, for interest's sake.