Too many map layers are like too many choices at the supermarket, its proven that reducing choice not only increases decision making but also makes people happier. If you are worried about catering for the small percentage of high end users then provide downloadable files as they probably have their own software anyway.
Drive search through simple search boxes and hyperlinks that people are used to, and drop the complicated navigation bars and icons that are not understood. Users don’t want to spend their time learning how to use an interface they want information. All those features and functionality might be great on the desktop but they just confuse and slow down the goal which is engaging the user and delivering information.
Single purpose maps engage users and deliver information in the simplest possible way, and create confidence in an organisation. They increase web traffic and reduce call centre volumes as well as provide a platform for articulating changes to large numbers of people in a simple format.
Single topic maps just work!