That's always a good idea to use each API in the most efficient way.
But there are weaknesses in epoll that make it not as efficient as poll in such intensive performance tests. As epoll API can only handle one file handle at a time, there are too many kernel/user land context switches. For example, three context switches are required for each non-keepalive connection just for event handling, while poll() only need one. poll() can combine multiple events in one function call, epoll() cannot. In this kind of performance test, usually multiple events will be combined and reported by one poll(), epoll() has to fetch them one by one.
The design of kqueue() in FreeBSD is better.
We can include your hssTVS in next benchmark update if it is feature complete and ready for production use by that time. :-)