Works for me (Score 2, Informative)

I work for an ISP that sells broadband wireles. In designing our network, I chose to use almost the exactly same setup as you described. PPPoE gives us a lot more flexibility than any other access control method. You can back it with RADIUS for simple user management, and there are a lot more client solutions out there, ranging from free to licensed. We've been running with few problems for over 6 months now with our current hardware setup. I'd suggest checking out MikroTik RouterOS. It's a linux-based OS that supports everything mentioned thus-far in this thread.. from PPPoE to PPTP and even IPsec. You can even toss a pci/pcmcia card in it and make it an access point which removes another device from the network.