DP1M tripod required.

Dave I do use a tripod a lot more with this camera, mostly for depth of field, but I'm not afraid to shoot ISO400 or more when hand held.  The images for my use process nicely.  Try going out one day and just experimenting with different ISO numbers.  IMHO there is no practical issue with ISO400.  I think capturing the image is more important than maximum quality and I sure wouldn't miss a great shot because I couldn't shoot at ISO100.