From the documentation, the advantages/new features of the new wireless package are WPA3 and Fast Roaming. Any other stability improvements?
Wave2 drivers so stability is also a lot better.
Also pure performance, quite some difference.
I can debate with it. I have many issues since I updated to wifi-qcom-ac on cAP ACs up to 7.13.5. 
My experiences are very good with the new driver (cAP ac, cAP XL ac, wAP ac).
In accordance with the benefits mentioned above.
Only disadvantage for now, most of the arm-ac devices are 16Mb storage only, so don’t count on putting other stuff on those things.
Purely as AP, very good move from Mikrotik.
Thanks everyone. I’ve got several clients with cAP ac’s so I’m just looking at one in the lab. I think the only hurdle I need to overcome is some problem with CAPsMAN and guest VLANs. The solution about doing the tagging in a different way is covered a forum post somewhere 
The VLANs work like charm on ACs also, but yeah, it must be configured on AP side, it’s a simple bridge vlan filtering. Extra config steps and not centralised, but works.
There is actually a help page about this:
https://help.mikrotik.com/docs/display/ROS/WiFi#WiFi-CAPsMAN-CAPVLANconfigurationexample: