Thank you for your questions.
- Migrating from WebDataRocks to Flexmonster does not require major code changes. Please see our guide for a comfortable and quick migration.
- We would like to inform you that ability to create a multi-level drill-down depends on the Highcharts functionality, not on our components. As it is possible to create this chart with Highcharts, you could specify it both in WebDataRocks and Flexmonster.
Please have a look at the example with WebDataRocks and example with Flexmonster. These samples have two-level drill-down, but you are welcome to implement the third level on your side.
Hope it helps.