Interesting way of looking at it Dave but wouldn't the compression be different as on the Sony you're still using 24mm although cropping in.
Sorry, I meant 2x for the crop not 1.5x..
Yes there would be a slight compressional difference I suppose, but at these relatively wide angles it would be negligible in the final cropped image and you can of course zoom in or out with your feet to compensate if need be.
I just thought this idea would give you what you want relatively easily and quickly and by utilising the 24mm TS-E lens you already have, which is about as good a TS-E lens as you can ever hope to own and by cropping into the frame, it will be as sharp as it is possible to get with any lens that has ever been made. And of course you also then have a high quality back up system that is equivalent to medium format in quality, that can also be used to easily convert your 24mm to a 43mm and a 66mm with little effort and as a bonus, you can double the length of all your other lenses by cropping if you so wish.
Dave