Don´t really understand your conclusion. Why to hell the K-5 (IIs or not), two months ago one if not the best APS-C camera sensorwise is now LOW in ISO performance? And what are the other cameras, that are so better? I really don´t understand your phrase, or you wanted to say that the GR ISO performance wasn´t up to the performance of other, DSLR-sensors?
Thank you very much for clarifying this!