To the best of my knowledge the FCCs are different. The issues with pitch control on the AW189 can't be solved simply by "installing" a Honeywell software. In the other hand the 189 AFCS is better than the 139 one in some other aspects. Although you would prefer the latter if you are facing bad weather conditions.
However it seems that Phase 5 has improved the overall behaviour by a complete software new design... we'll see.