I think the whole point about that, what's happening now, is that Luffy gets back full control of himself, by getting a hold on Nika.
That "this is my free form" sentiment and "who's that Nika guy" stuff needs to vanish, he has to get in charge, so that he controls the DF and not just lend strength from it, whenever he needs it.
He treated the Nika powers like a different entity "my heartbeat is coming back" and such.
It shouldn't be normal that his DF influences his personality this much. This just goes to show the conflict Luffy has with the Nika fruit.
When all is said and done, he should have all the powers, but w/o the personality change.
And I guess the beast form mastery will cover the timelimit aspect to some degree, cause now he can have a legit hybrid form..?
So definitely much less annoying in terms of personality & time limit issues I think.
Imo the result will likely really be a SSJ4 like transformation, basically hybrid Nika 1023 Luffy.