Hi Paul,
I have my Surface Pro 3 since two weeks now, it is an amazing piece of hardware.
Lightroom works absolutely perfect, but thats is to be expected since it is a standard Windows 8 operating system.
What amazes me is the fact that you can actually judge your sharpening on the monitor and predict how it will look on print, thanks to the hight resolution.
I have not yet profiled the monitor, but colors seem to look ok so far, no problems with the gamut. I don't know if I will do color critical work on the SP3.
Overall operating speed is great, but this may be dependent on the configuration you buy (I went for the i7, 8 GB ram, 512 GB HD, the most expensive...).
Editing with your fingers on the screen is absolutely possible, you can also use the pen.
Presenting your work as a slideshow looks gorgeous.
So far, I'm very happy with the SP3 and would recommend it to everyone looking for such a device.
Greetings from Switzerland
Ludwig