Okay, all the linoleum has been removed and the floor has been screwed down. It took almost 10 Lbs of 8x2" deck screws, but it feels very firm. I've walked the entire floor and have not heard a single squeak.
I am, however, concerned about one area.
Right smack in the middle of the kitchen, I seem to have a "bowl". I used a 6' long straight edge and have found a dip, in one direction, of almost 1/2" and going perpendicularly, a dip of about 1/4". You can see what I mean in this pic.
Should I do something to address this now, or should I just wait and fill in as much as I can when I thinset the hardiback into place?
Randy