tagging of surface.

This decision is very much a personal one at this stage, and to a certain extent will depend if you have particular use-cases which might benefit from the more detailed mapping.

Most people choose your first option, ignoring small sections of paths with variant surfaces. In general people do not do this because to do it consistently would limit mapping things which might be considered more important.

Areas where such information might be more immediately useful will typically be places such as university campuses where additional information for people with limited mobility or sight might benefit.

There is no harm in trying this out in a limited area to gain experience, and perhaps have concrete examples to show to others. I presume we will be seeing a lot of micromapping (as it is termed) as mappers constrained by where they can travel add information in their local patch.

Looking at the pictures and thinking about the things I find important, I would want to add the following information:

• step_count: Number of steps (it can be useful to split the steps into 2 flights, just as you might for the surface).
• handrail: Absence of handrail. This can make even short flights of steps harder for some people.
• tactile_paving: Absence of tactile paving. Navigating this area may be harder for a blind person because this is lacking. However the change of surface may be anticipated to provide the same effect.
• lit=yes: the stairs are lit (at least I assume I see lamp posts in the images)

As you can see once one starts considering the detail they may be even more. Only you can make the judgement as to what is appropriate right now. Ultimately these details will eventually appear in OSM.