They will try and take them down the stairs as they were shipped. From my experience with NAVL, they are just that, ''manpower''
When it arrives, all that other stuff will be on you

Depends how narrow your stairs are. Moving a pin on it's legs is pretty safe because you can put it down when tired and keep it stable. When you take the legs off, be prepared. Make sure not to let it get to the ground (if possible, unless you have a dolly) to ward off potentially chipping the corners or worse. If you have to put it down, have a strap for the head, etc. If you have shrink, that's a plus too, to keep it from getting dinged.

Just disclose what you need done before they get there. For a fee they do stairs and yes so I am told with the legs on. Never seen it done personally, but you could call Michelle Bianci @ NAVL and ask about finer points of the move.

Yes it can be done. I used NAVL and paid extra $98 to get my first pin upstairs. See my story on it if search NAVL as tag name on trip from NC to AZ. The guys who first delivered it where unable to make if up my stairs with legs on and complained there was too much of a tight turn where they needed to lift game up on over a section. So they had to call there company to rearrange and game sat downstairs for a few days. Upon working with the local sister company that Navl used they tried to want to charge me another $98 bucks bec they wanted 2 mord guys.I called Michelle and told her I would not pay another fee for this bec if was orginally quoted. In the end the local sister company finally sent two nice guys back out. One was the size if a house and they took the legs off and wrapped my game in a blanket. They used straps and moved it up my stairs one by one. They were familiar with doing this and everything worked itself out. Great two experienced guys the second time who knew what they were doing unlike the first to guys who did not have a clue and unaware pin needed to be moved upstairs even thou it was on their paperwork and I reminded them when they called for delivery. Just make sure they send people familiar with doing it and it should be fine. It appears they tried to cut corners in the beginning to save costs and tried to increase them by wanting more manpower.

If you're paying them to move it up/down steps, let them do it their way. You can take a pin up/down steps with the legs on without removing the balls, no problem. If you want the legs off, balls out, and the machine on a dolly, you should have the ratchet handy and help them do it your way.