It works just fine with a pi3bAgree. Pico board was deliberately simplistic to give best bang from a single pi zero, and aimed to completely automate a pico reef . I think it was a good decision since even with pico it took more than a year to sort out everything (note: ph driver is still not available in stable release yet). We do had discussion around more beefier, feature rich system, but we wanted to iterate with small setup first. I also wanted to understand the pros and cons of clustering multiple independent controller vs having a single powerful one.