IME, the toe flip becomes natural, same with clipping in and out, takes some time and experience. The flip is still necessary with dual sided spd pedals. The thing I do not like is the toe area getting significant wear from doing the flip. Even shoes with a toe cap show the wear. It is an aesthetic thing, I wind up using shoe polish or a marker pen to mask it.
The drawback on the spd-sl’s is twofold, the cleats wear out much faster, and it takes a low number of steps to speed that up dramatically. To mitigate that, a cover for spd-sl cleats works well. One just has to remember to bring them on a ride, and to put them on. Obviously, if you don’t get off the bike, not an issue.