The answer to the question - SHOULD I keep a DSLR? The answer is - Maybe.
Two reasons -
Firstly - For commercial and commissioned jobs for new clients will I be taken seriously if I don't turn up with one?
Secondly - High ISO performance.
The first is an issue that I will address at some future time but I decided to have a look at the second reason with the cameras I have already. I have not included the 550D as the 7D is so similar in terms of results.
Ignoring the fact that these are taken with different lenses, with different ratios, the following was an indication of how each camera performs. I used the fastest lens I have for each system, all wide open. From f/1.7 on the GH1 to f/2.8 on the X1. The Leica only goes up to ISO 2500 so the ISO 3200 example from that camera was slightly underexposed and lightened in Photoshop to "simulate" ISO 3200.
As ever clicking on these images leads to a larger sample on flickr.
There's a clear winner and looser here, and the winner isn't the 7D! To my eyes the Leica X1 is the cleanest, the sharpest and the most pleasant to view. The worst is obviously the Olympus E-P2. The GH1 isn't bad, but what you can't see is the banding that affects the rest of the image. I hope (and pray!) that the GH2 finally fixes this problem. The Leica M9 is not great but I could have got a better result using raw. (These are all jpgs.)
I knew the X1 was good in low light but I didn't think it was this good. Its a shame its a fixed-lens camera that is somewhat slow to operate. Any bets as to whether this is the basis of the sensor that turns up in the M10?
Its an unscientific test, but bears out much of what I've thought for some time. That a DSLR isn't necessarily superior for high ISO performance. Certainly as regards APS-C sensors. Full-frame sensors like the D3, D3S, D700, 5D MkII, 1DS Mk III etc. are better, but I'm not going to be getting any of those.
So in terms of high ISO noise performance I believe that I can work without without a DSLR.
However I think a bit of "pimp your Panny" is required before I can address the other issue!!