I carried and installed a Canon Pro-2100 which is lighter than P7570 but not that much, with the help of only one friend. We are both average strong. Here is how we did it:
i) We wrapped the bare printer using two thick moving blankets. We made sure it's covered on all sides.
ii) Since the new printer is empty of inks and all loose parts are taped and secured in their places, there is no movement inside the printer. Therefore, there shouldn't be any problem in tilting it. I can say so at least for my Canon printer but don't know about Epson printers.
iii) We strapped the printer to an appliance dolly using two straps (up and down).
iv) We carried it up to the apartment through a staircase step by step. There are videos on Youtube showing how to use an appliance dolly. The key is to make sure printer doesn't get any shock in the path. This can happen when there is bump (like in some door frames) and once the printer goes up the bump, it is going to fall on the other side. That's when the second person (not the one who has the handles) must hold and control the dolly from its bottom so it descends slowly and smoothly on the other side of the bump.
v) Inside the apartment in order to put the printer on its stand, we did it in two steps. First, we put it on my flattened futon sofa bed half way up. Then, we lifted it one more time and put it on its stand.
I could have had more help for carrying the printer but I trusted this method more. Imagine 4 people trying to carry it through narrow staircases and door frames when two people can not pass at the same time. In such tight spaces frequently, some people would give up and step aside (it has happened to me before). It may end up being carried by two people instead of four.
If I need to ever move the printer up or down over a staircase again, I will empty the ink inside (Canon has this option in its menu setting to prepare the printer for moving) and, tape and secure the loose parts (like the print head). I have kept all the needed pieces for this and for the record, I have taken pictures of all areas that were taped and secured before removal. I will use my appliance dolly again for the task.
PS. By no means, I encourage other people to do this. However, if for any reason some are pushed or want to do it as a two people job, this is one way to consider. Of course, you need to convince yourself this is the right way and have confidence in what you are doing. I had imagined all stages of the move in my mind and carefully reviewed the path before attempting it.