I have tried Cisco 887VA with both ADSL and VDSL modes and it works great alongside Meraki MX 64.
When using SOHO Huawei and ZTE ADSL modems, my client refused to use bridge mode, so in that case I had to disable their onboard firewalls/WIFI and set DMZ to Meraki DHCP-obtained WAN IP, so Auto-VPN would be green-lighted.
It would be nice if MX had PPPoE dial-up support in the Uplink dashboard, for either WAN1 o WAN2.