When scanning the AP goes out of service momentarily and is not servicing clients. Say, for example, the AP is serving clients on channel 6. Now it goes to scan........it changes to channel 1 and scans for threats for 110ms (variable), then goes back to Ch. 6 for clients for 10 sec. Then it goes to Ch.2 to scan and back to Ch. 6, etc.
If there are no apps that are latency sensitive, like voice, this may be just fine but if you do have sensitive apps a dedicated solution is better.