Thanks, this is exactly what I was hoping someone would have done and done far more comprehensively than I could ever have imagined doing myself. Extremely versatile website and after doing some various testing it shows that for a 'locked frame' as they call it, where the size of the subject remains constant, the 56mm has a shallower depth of field than the 90mm. As many others have noted the difference in perspective between photos from the two lenses is more pronounced in the simulations that the difference in depth of field but good to know that you don't need the longer focal length to get the shallow depth of field. As much as I want the reported sharpness and quick focusing of the 90mm I think the first one I will buy will be the 56mm given the increased flexibility of the faster aperture and increased versatility from the smaller size. I suspect the 90mm won't be far behind though.....
Thanks again for all of your comments.