I used my D5100 for everything when I had it. Walk around, Landscape, and Sports Events. I especially like shooting 1080p at 30fps with the swivel LCD. What I did not like was the lack of a lock on the multiselector. I let it go when I got my D800 because the batteries and SD cards match on my V1 and D7000.
If you want a smaller lighter walk around setup, get a Nikon 1. That's what I have my V1 for, and with an adapter I can use all my Nikkors. I can fit a V1 with 10-30CX lens in my large pockets.