Just a comment on the 'street' shoe use and quick runs to the local store.
I used Shimano M520's and now Time ATAC XS and both have enough platform to let me easily and safely ride a mile or so at low speeds (~10mph) on low use streets in my hood to get a coffee or go to the convienience store. This is in dry conditions.
If I am going futher I put on SPD sandals which are as comfortable as a regular sandal.
Al