I see people writing that they want to see the image quality of the new HS20 to see if it can compete with entry level dSLRs. This begs the question of course on what “compete” means. I.e. on what criteria will you judge?
Well, my criteria is always how the camera handles high ISO, because as the light gets dimmer you need to crank ISO up to maintain shutter speeds. Even outdoors in the evening, you are often shooting at 800 or 1600 in order to keep people looking sharp on the image.
So I always compare cameras at 1600 ISO or thereabouts to see how they fare.
The key to understanding that dSLRs are in a different class of image quality is to understand that there is no substitute for sensor real estate. The bigger the sensor, the better the image quality, all other things being equal. So far, comparisons between the HS10 and HS20 have not shown much improvement. But then, the people shooting the HS10 are always shooting it in HR mode, which is not what you do when you want better low light imagery.
Still, there is only so much improvement available, and the fact is that the APS-C dSLRs retain more detail at 1600 ISO than the HS10 does at 100 ISO in low light. So the classes are so far apart as to eliminate any competition at all.