I agree that the Nikon ES-2 with the 60mm Nikon macro lens is an awesome combination. It is far faster than scanning with my Nikon LS dedicated slide/film scanner which is going up for sale!

If you love SHARP focused images you will love the higher resolution lcd monitor for tack sharp manual focus. When tripod shooting I use it exclusively. It blows away the 810 monitor. My photo buddy who bought my 810 now wants the 850 for this feature alone!

I own most of the lenses you are considering and for me, without question, I would be taking the 12-100 f4 pro if I were only taking 1 lens. The additional IS the lens provides more than offsets the f4. It is a wider angle, lighter and smaller than the f2.8 Pro. It is most likely the ultimate travel lens in the Olympus lineup which is why I purchased it. (I recently put an ND filter on this lens and shot waterfall shots at 2 seconds hand-held which worked incredibly well!)