We've been using HAProxy 1.5dev in production for a few month, including SSL. It's been one of the most simplest and stable parts of our infrastructure.
A bit of self-promotion, but you may want to take a look at bud ( https://github.com/indutny/bud ) too. It is basically a TLS terminating proxy, and does support some availability features (if you need them).
The bud is built on the top of the libuv, which empowers the node.js.
I was doing about 8GB/s sustained through 1.5 on a single box without issue.
However, you need to run it in multi-process - I found 16 to be a good number. The only drawback is that any monitoring you do is on whichever process you happen to connect to when you check, so you need to multiply by the number of total processes to get accurate numbers. Not sure why the monitoring is per-process, but it's a bit of a pain.
It's not very heavy. Usually between 1000-2000 concurrent sessions during the day. Connection and session rates peak around 200/s. Single process. CPU has remained under 15%.
we're still using stunnel for ssl, have been waiting for positive reports to let haproxy do it, but are optimistic.