I'm still looking for some information on R320 and M510, but they are likely similar to these other 802.11ac Wave2 models.
Technical Specifications: Max Clients per Radio by Auth Type
Note: "<100 per AP", means up to 100 clients per AP; "<27 / 2.4G" means up to 27 clients on the 2.4GHz radio, etc.
Encryption = None TKIP AES
Max Users/Radio Max Users/Radio Max Users/Radio Max Users/AP Concurrent VoIP clients
R310 <100 per AP <27 / 2.4G, 100 / 5G <100 per AP 100 < 30
R320
R510 <512 per AP <256 / 2.4G, 256 / 5G <512 per AP 512 < 30
M510
R610 <512 per AP <256 / 2.4G, 256 / 5G <512 per AP 512 < 30
R720 <512 per AP <256 / 2.4G, 256 / 5G <512 per AP 512 < 30
R730 <1024 per AP <512 / 2.4G, 512 / 5G <1024 per AP 1024 < 60