So I've just downloaded the Beta and it finally does seem to work (even though its not listed as being fixed?).

Anyhoo... I can now see that the implementation of Document Resize is completely baffling to say the least (as I feared). You have to set the units to Pixels. If you use any other unit it simply resamples even when you untick resample. This is just stupid and confusing! Something that compounds the confusion is the UI whereby you are unable to see the what the changes you input will be, so you have to go through with the operation you might not actually want by clicking resize, then open document resize again and then choose another unit to see the changes. If it simply showed the pixel dimensions in the window along with the chosen units and it updated live without having to click resize and then reopen document resize, it would then be just about bearable to use. WAY too many clicks are involved in a needlessly complex implementation. The same as the colour picker tool and the tab order in the Transform palette. The UX seriously needs looking into in my opinion and the UI in parts.