I do it now out of KPDX to multiple locations, although I use the Embraer 120. The key is to choose routes that allow you to turn the seats over a minimum of 6-8 times per day - that means each aircraft needs a minimum of 3-4 flights per day, 7 days per week (during hours that people really want to fly - no 00:00 - 05:00 flights. Typically, this means choosing routes that are about 300nm or less. And fly to each distination at least twice per day (an AM and a PM flight). If you are already flying Dash 8's then adding another couple won't hurt you much. If you are thinking of adding Dash 8's just to fly short-haul then make sure you have enough short-haul flights to justify it or fleet commonality will eat up lots of profit.