Been using the old Logitech ergonomic model ('Cordless Desktop Pro') every day for 10+ years and have a spare on the shelf. Glad to see they're bringing it back.
Just my personal preference: I like the numpad and multimedia keys to be present on the main keyboard. So I have more keys to program, and the numeric pad is closer for my hands to travel. I will probably buy the the K860 anyway, even though the multimedia are now part of the function keys.
MicroSoft Sculpt is very comfortable, but hopefully MS can replace the physical lever that toggles the function keys to/from multimedia, with a normal (modifier or otherwise) key that can be tapped in an instant. And attach the numpad to the main board.
But I encourage all companies that manufacture and experiment with ergonomic devices.