DrayTek make some good devices, I use two myself (as bridged modems into a Firebrick 2900, a Vigor 2862 and 2860). They also act as handy backups should the Firebrick fail for some reason.
Some may say Broadcom (Zyxel uses the Broadcom chipset) works better for their line, while some others may say Lantiq (DrayTek uses the Lantiq chipset) is better for their line. One chipset doesn't fit all lines unfortunately. In my case Lantiq works best on both of my lines, I'm also connected to the somewhat troublesome/archaic ECI DSLAM, FTTC/VDSL2.
Regarding your scenario, I imagine it would work.
Edited by Ixel (Fri 01-Jun-18 15:50:16)