Thats more or less what I did, and nix just made sense for the job. For 99% of people I'd say no its not worth it to tinker, just go with opnsense virtualized so you get at least some the benefits of the better linux drivers. By that I mean NBASE-T on various intel chips and while intel's igb is fairly solid on unixes many other vendors' drivers are less so. However if you're willing to figure out configuring per your needs you definitely can get a lower latency router with all the same capabilities and more, with it's components more sanely isolated via containers.