I am using HE 6in4 bgp tunnel to announce my own IPv6 space in my home for a long time without a problem. Recently, TWC adds native IPv6 support in my area. So, I get a /56 (From TWC) and a /48 (From ARIN) prefixes. I tried to use /56 for all SLAAC assignments in all vlans, and /48 for all static assignments. However, routeros cannot set to route TWC ip to TWC interface, and my IP to HE Tunnel.
For now, I route all traffic to HE tunnel. It is working, but it increased the latency for native IP. Also, it creates asymmetric route.
Hopping mikrotik adds policy routing for IPv6 soon.