first things first, E3 isnt a low light camera. It can and does support shutter speeds in 'kinda' good light circumstances without issue, i shoot fairly frequently at 400-800iso in ambient light circumstances using flash just to fill.
800iso 1/60th F4, 11mm
400iso 1/30th F4.5, 11mm
on the sensor, this is without question the best 4/3rds camera to date, the much discussed noise is not so very far from APSC if it is at all. Would you really use 40D over iso1000 for colour professionally? If you convert Canon APSC sensor are to 4/3rds the sensor is about 16% smaller. The DR being so similar means to me the well sizes are about the same. On sensor density specifically:
4/3rds Olympus E3 = 41,563 (10.1Mp); 243 sq mm
APSC Nikon D300 = 33,300 (12.3Mp) 369 sq mm
APSC Nikon D40 = 16,260 (6Mp) 369 sq mm
APSC Canon 40D = 30,792 (10.1Mp) 328.56 sq mm
APSC Canon 450D = 37,195 (12.2Mp) 328.56 sq mm
reasons to be with 4/3rds in the first place, the lenses, the quality of the glass is consistent and of professional quality. The top end choices are truly top end glass, and Sean you might have your wife check out 14-35, 35-100, 12-60 SWD, maybe even 7-14.
reasons to be with E3, the features, LiveView is ever more useful with an articulated LCD, the OVF is a generous size (mine has a 1.2x mag finder making it bigger than 5D) IS, dust shaker that works (i have no idea how to clean a sensor BTW)
reasons to my mind to pass on E3, low light photography, the weight compared to other 4/3rds cameras (although on par with APSC), the complex menu system. Perhaps a tendency to deeper DoF
one more completely unnecessary gratuitous E3 shot
640iso, 1/40th, F5, 16mm
