I don't know what type of photography you do, but I use mine when there is lots of white in photos and it doesn't have to be on a sunny day. I shoot horses and one Jumper show I shoot has big white tents that get wet in the rain and then it'll brighten up a bit and it blows the white out and it's too dull to use a polarizer, so I turn on highlight priority mode and shoot in RAW and if I need to use the recovery function in CS3, it works just fine and my white tents, which are actually a very light grey/white, comes out nicely. You won't be able to shoot below 200 ISO though.
