I don't think an RWS with a 25/30mm gun on Hawkei would get much support. It's hard to imagine how you would employ such a capability, at least in a way that would be worth the cost and training burden.
As I've mentioned before, I think having Hawkei allocated to the Reserve RAAC units with a mix of .50 cal and 40mm AGL, on a mix of protected swing mounts and RWS, is the way to go. Add a Javelin/Spike to the RWS, and you have a very handy capability. In the reinforcing battlegroup construct, you have a very mobile and well armed capability well suited to RASO tasks. The mobile anti-armour capability is a huge plus, as it's hard to imagine how you conduct RASO in a conventional conflict without this capability. You probably couldn't afford to train the Jav in large numbers in peacetime, but it would be easy to pick up that skill during the lead up training inherent in the ARES notice to move.
Such a capability would also be very handy for the ARA as well. As it stands, in ten years time the combat brigades won't have a combat vehicle less than 30 tonnes in weight, which makes rapid deployment and deployment to secondary theatres difficult. Having the capability to draw on ~10 tonne vehicles that still have a very handy armament, mobility and comms fitout would be very useful.
As I've mentioned, if I was in charge of the Reserve armoured capability, the RAAC regiments would provide three capabilities - dismounted cav scouts to slot into the ARA cav squadrons, Bushmaster's to lift the infantry combat teams, and Hawkei to provide an ISR/RASO/SASO capability, as the light counterpart to the ACR's heavy capabilities.