Does anyone know about read/write speeds on SD cards and their relevance to real world application. I have just bought a Pentax 555 and started looking at SD cards and came across write speeds. The average spec is 1.2 - 2 MBPS, whereas some Panasonic, Simpletech and Lexar cards claim speeds of up to 10 MPBS. In fact Simpletech differentiate their high speed cards by labelling them with a PRO label. Would they higher speed make an appreciable difference or are cameras only able to write at fixed speeds. I can imagine a difference when uploading to a PC but I'd like to know/understand the difference from the camera side of things. Any help would be greatly appreciated.