As long as it will fit through the door and up the stairs in SOME orientation, you can get it in... They are shipped with a ton of shipping protectors (all the blue tape we spend hours ripping out of printers, plus the plastic gizmos that keep the head from moving), and are designed to be taken out of their box on the street and then moved up the stairs without the box.
The bigger issue is whether you'll ever get it OUT again... Once the ink is in, Canon printers have to be moved essentially flat, especially the 44" models - I was present when an 8300 died this way. The best information I have is that the Epsons are somewhat more tilt-tolerant, but I don't know how tolerant they are or aren't (My 7900 will actually clear the doorway flat with about 2 inches to spare, so it will get out when I need to move it). If you're planning on keeping the condo for the life of the printer, this isn't an issue, but if you're planning to move, it very well could be!
Also, remember just how big these printers are in terms of how much of a room it'll take up. A P9000 is about the size of an upright piano, and it's a fairly industrial looking object that doesn't blend in to most decor. If you have a studio room dedicated to it (or shared with your computer or similar things), it's great. I share my bedroom with a 7900, and it reminds me of the stories of the old Royal Navy, when there was always a large cannon in the captain's cabin - there's not much way of decorating around a cannon (or a 300 lb printer!)
