This product is not only usable for internet providers, but also suits perfectly for needs of test labs. I looked for an ability to test hi-performance routers vs different types of PPP connections and did it under FreeBSD, but now accel-ppp allows me to do the same things under Linux. The configuration is relatively simple (whenever you know what to configure :) ), it does not consume a lot of CPU, it works pretty nice in IPv6 mode. The only thing to be improved is a documentation. The manual is very narrow, not all compilation or configuration options are described.
Good fast and enough stable universal PPP daemon.