Does anyone have evidence of this, or is it just pure speculation? I've seen many examples of Hot Toys improving their product over their prototype. A prime example is their release of The Peacemaker. I don't recall Inart announcing their release of this figure, so I didn't see any incentive for Hot Toys to put in the extra work, other than to maximize profits.
But I would expect Hot Toys to do this for many of their releases, especially a release like The Batman, in making the best product available based on their timetables.