Field-Programmable Gate Arrays (FPGAs) are gaining considerable momentum in mainstream high-performance systems in recent years due to their flexibility and low power consumption. Still, FPGAs remain largely unavailable to software programmers due to programming and debugging difficulties that are inherent to standard Hardware Description Languages. The performance that hardware-oblivious software engineers can expect from migrating legacy code to FPGAs remains shrouded in mystery. To gain insight on how to use FPGAs in high-performance computing, we created four different systems and evaluated them using benchmarks from the Rodinia benchmark suite. The systems we evaluated were diverse in both programming model and generality, and range from a custom-built 30-core manycore system to FSM-based accelerators using LegUP and deep data-flow pipelines using Intel FPGA SDK for OpenCL. We found that the original version of LegUp does not achieve very good performance out of the box; still, with some non-trivial modification in the architecture, we improved its performance by up to 10 times. Despite this, we found Intel FPGA SDK for OpenCL to perform up to two orders of magnitude faster than LegUp. We also found our general-purpose manycore system to have comparable performance with LegUp.