Yes it is rated to out put 8.9A, divided by 9 COBs that would be 989mA per COB. But in practice it will put out up to 9.7A or 1080mA per COB when adjusted to max. The driver would probably pull 367 watts total at almost 95% driver efficiency.
As far as pros and cons, using the HLG-185 series approach you get up to 190V on the heatsinks so they probably should be grounded for your safety. Wiring in series is simplifies the wires routed through your space.
The HLG-320 with parallel setup would be less than 36V so not as likely to be able to get through skin. Each COB might be getting a slightly different current but probably not a significant difference. Wiring in parallel results in more wires overall.