Worked in the imaging industry a looong time before moving on to the more modern shaving business...the little Pen's a spiffy camera, and I'll hereby make a drab prediciton; 5 years on from now, only the flagship cameras from Olympus, Nikon, Canon, Pentax, & Sony will sport an optical viewfinder, and they'll be made of glass. The majority of the lens-changing cameras will be of the Pen and Panasonic's style, thinner by half because of no mirror and no (optical) viewfinder. When you're behind the counter now and watching even a 25-year-old come shop a camera, none of them even try looking through the viewfinders. It is foreign to them.
I say go for the smaller camera and don't look back; the pictures from your little guy you're always bringing about are so much better than those ones you don't see from the bigger D90 left at home for its weight and mass.
