General elastic performance when search_after with PIT sorted by score is used for UI pagination

We are integrating search_after query to our UI pagination. If we use PIT and keep the search context alive between UI page fetches, which could be minutes depending on user think time, would that scale well?. We have to support at least a few hundred concurrent users.

Also how would that affect other searches and the background ingestion process?. Documentation says lucene segment merging is impacted by open PIT contexts. We have a fairly rapidly changing large index.

This has been answered in Inconsistent results when search_after is used for pagination sorted by score and id