Can I use third part APs with an MX68 security appliance?
I have robust WiFi coverage in place already from another vendor. I would like to benefit from all the security features the MX-68 with advanced security license offers across my network, including wireless. So long as the APs are behind the MX, shouldn't clients connected to those APs benefit from the MX device?
Certainly @KA that's fine. Depending on which 3rd party APs you're using, you can either have DHCP services provided by the MX, or by the standalone APs if they're able to do so. Regardless, like you said, clients on the APs would benefit from the security features of the inline MX, just connect the MX68 WAN to your ISP and hang the APs off of the LAN ports.
Yes this is a common scenario we have, when taking over sites and beginning the change or update of equipment. We usually start at the gateway to secure ingress and egress into the network then work back replacing the network equipment.
If your gatway of your AP is MX so you are able to use the benefits, but if not, like you conentrate your flow to a VPN like @BrechtSchamp said, then you'll not avaible to use benefits of no one vendor.