There are lots of features:

* Asynchronous SNI - you may load cert/key pairs on the fly and let bud know which backend do you want it to connect the incoming client to

* Asynchronous OCSP stapling

* TLS ticket rotation, with possibility to scale to the big cluster

* x-forward frame for SPDY, and soon for HTTP/2 too

* Lots of other features, but nothing bud-specific