I'm a strong proponent of staying with vendor firmware on DSL equipment. DSL is such a dicey technology, running on crummy copper lines, with lots of odd protocol options, variations, etc (and ATM (?!)).
It gets hard to defend an outage/trouble report when they ask, "What kind of modem do you have" and you start to tell them that you hot-rodded the modem to use some lunatic firmware with anti-buffer-what? :-)
So I stick to using their modem. That goes double for a Zyxel that's bonding two pairs: just plug the LEDE router's WAN Ethernet into it, and the bits go in and out. Don't peer too closely at the man behind the curtain/sausage being made. If they're not delivering anything close to their promised/estimated speed, then you have cause to complain.
In their defense, I will say that the Fairpoint techs on the support lines are halfway (or quite) knowledgeable, and are supportive of either of these cases:
- I run my own router.
- I put the DSL modem in bridge mode, and let the router supply PPPoE credentials
But letting Fairpoint-supplied equipment handle the physical link seems good to me.
My two cents...