I have a contract handed to me to create a google map interface for a real estate company where the area they are operating is moving sales around in extremely high volume. To date, I have created 12 maps of polygons of zip code boundaries. The 12 maps are attached to a single, multi-column spreadsheet in Google fusion tables, and each map uses a different column to create a value-based fill color.
Now I'm being asked to create heatmaps for each zip code. Unfortunately we are looking at thousands of markers per zip code, and potentially we will need to heatmap zipcode against zipcode. The Proof Of Concept zipcode has over 16,000 markers (lots of homes).
My question is this: At what point do you tell your client that google maps will not work this far for you, and you MUST think about switching to a GIS server (ie. mapserver) to manage your interface?
Of note, he is renting these maps out as service for real estate managers around the area, so the traffic on this website will be high.