In T3127#168455, @Viacheslav wrote:

Implemented in 1.4-1.5 T5248

Yeah, in my case as well, NPTv6 is mostly only useful if it it works with a dynamic (from DHCPv6-PD) prefix, since that's how my ISP provides addresses (AFAIK I'd have to pay for a business connection to get a static prefix, though I haven't actually called and asked myself). I'm tempted to play with hacking something together by building from source myself with some tweaks to auto-update the nat rules when it gets a new PD prefix.