Floorplanning is an approach to improve the scalability of existing CAD algorithms, facilitate team-based design, and also plays an important role in partial reconfiguration. This work introduces HETRIS, a new automated floorplanning tool for heterogeneous FPGAs. HETRIS uses an adaptive legality approach to target arbitrary FPGA architectures. It includes enhancements enabling it to run on average 15.6× faster than previous work, while producing denser floorplans than a commercial tool. Using HETRIS we perform the first evaluation of an FPGA floorplanner using real-world benchmarks, allowing us to investigate the relationship between partitioning, floorplanning and FPGA architecture.