Bill is absolutely right, but having it with you - that's the key. A wonderful medium format camera and lenses too heavy to take with you are useless, as I have found.
My apologies, but I include the following non-MF image to make the point that a heavyweight monster left back at home is not a useful as a lightweight high quality compact camera taken with you. Particularly as one gets older
This image was stitched from 2 rows of 5 images each using a Sigma DP2M, Fanotec Nodal Ninja 3II pano head and a very compact Induro tripod, carried in a Domke vest, all of which weigh very little and do not spoil the enjoyment of just walking around selecting locations and enjoying the moment. Original image is a very sharp, very detailed 30" x 43 " at 300ppi.
This is why my MF kit is now largely confined to the studio.
Sunset over Downderry, Cornwall, England, January 2015.
The same principal applies to a Sony A7r or its successor, only if the Sony A7rII has 50mp, you can save on much of the stitching. Heck, the Sigma DP2M is only 15 (Foveon) MP. The key (for me) is to have the camera with you and to enjoy the moment without the heavy lifting.