You can scale the simulator down to 50%.

And if you don't need the window chrome, you can fit almost all of the iPad simulator onto a 1440x900 display. Enough so that its definitely usable.

The high res 15" screen is suitable for every resolution/orientation of iOS devices currently available.

Uh no. The hi-res screen is 1050 high. Which is not enough for the iPad simulator in portrait mode at 100%. It works because the simulator simply gets scrollbars, but I find that very annoying.

The 17" is 1200 high. Which is is good for any iOS device in the emulator.

An iPad is only 1024 high, does OSX have a way to disable the window chrome?

That would be a nice hack! Bring it on!

Megazoomer works on the iPhone Simulator in iPad mode: http://ianhenderson.org/megazoomer.html