hey for once Im not the old fart luddite--I have loved good ol shimano mtb clipless for about 20 years, 19 maybe. There are loads of spd shoes that are more walkable than others, but even my mtn specialized whatsit shoes with really nice stiff soles and great fit for me, are walkable in...not a lot , but into stores etc without any skating.

all I can say is go do some hills with a crrapload of stuff on your bike, with and without clipless, and the added efficiency will show up pretty darn quickly.
Everyone has a preference, but seeing you are used to them, take some sandals along with you and use spd's.
I have some real old ones Shimanos that go back to maybe 92, and a new set of I think 520s, $50 here in Canada, prob less in the States. Simple, light (ish) small and cheap.

or dont