One thing I have done over the past few days is to make my menus all fixed width. It is acceptable for most of my system to be fixed, although I don’t like to do it in all cases.
What I noticed was on mobile devices, especially ipad2, I was getting some pretty bad screen formatting issues when I was running menus with widths set to 0 (the auto adjust mode). It wasn’t even that the was any room on the screen for the menu and the iframe container… it didn’t matter. If set that way, the various grids and apps inside the widgets would just get cutoff, etc. As you said, it must have to do with the way Safari handles scrolling. I did also notice some more minor issues with android, which I hadn’t noticed before, so that is why I ended up with the fixed width solution.
On a philosophical note, I have spent so much time wrestling with browser issues over the years (and mobile just makes this worse), wouldn’t it be nice if we could have a universal browser test set, and then the stupid browser designers could do whatever they wanted (as they seem to do now anyway), but we would have a way to detect and adjust our code to their variations of implementation.
Oh well, it is 12:32 am on a Saturday night and I am still messing with SC! LOL. So I may not be making any sense tonight 
Peace everyone,
Jamie