Yh thats how consumer products work; they're set to work with preconfigured settings, then they never get updated lmao. Peeing your pants in winter to stay warm (a tad later it's cold af).
Despite what product, if it can be bridged then it won't matter tho, like you said PfSense behind the modem and you're golden.
pfSense for the win!
You can harm your performance, you can also improve your performance. It depends on your connection and isp dns servers.
I always use alternative ones because my ISP blocks too many stuff, and I don't really like that.
But if you want to know what is best for your situation, it's best to run DNSbench, you can download it from grc.com.
It will test your isp dns servers against pretty much all the other dns server options out there, and then give you a list sorted by best performance.
Then use the top 2 or 3 that you trust. In many cases these will be the ones from your own isp. If it isn't your isp has shitty dns servers and you will most likely be better off with different ones.
Also run these test at various hours and see if the results remain the same during peak hours.