That's just a recommendation. It depends on the applicationWith 80 devices on 2.4GHz are you using same channel APs or separate channel APs?
Even my small business Cisco AP only supports 50 active clients per radio and 200 connections per radio and each AP has 2 radios. And yes the Cisco AP has a 2.5g port plus an extra one 1g port so 2 per AP.