I have been using similar hardware setups in A LOT of installations. This is mostly an issue with the pfSense hardware. There's a lot of decent options around $200, mostly focus on getting a modern CPU (if it supports AES-NI there's a good chance it will be fine). A lot of them have 2.5g nics these days too.
Sadly, sg300 line is also getting pretty old. In recent years I'm seeing more and more issues with them, especially in the models with poe. Sg350 is even eos now, with cbs350 being the current.
I'm also now using r610 as the absolute minimum ruckus ap. I was using r510 for a long time, but the r610 has noticable improvements.