Sidi uses similar stiff soles on both the MTB and road shoes, so there is no meaningful advantage to road shoes. You may be told the road shoes are lighter, and that the SPD are a bit wobbly in comparison to a road cleat. But that is nothing if you need to walk or stop frequently in traffic.

Replaceable soles won't come into play unless you do serious walking or running in them. If you haven't worn down shoes in the past, you probably won't now.