How often do you find that your sensor needs to be cleaned (if at all!) When your "out in the field" switching lenses, how do you avoid the dust thing? Do YOU clean it or send it in for cleaning? Some of the Olympus DSLR's E300/E500 have a feature that vibrates or pulses the sensor,which supposely eliminates the need to clean it! Apparently, this happens every time you turn on these cams! (Slows the startup time though!) Anyways, I would like to get some REAL world feedback from you DLSR peeps on this! Just so I know what to expect and am potentially getting into here! Thx! Joe