I don't see the Chieftain being lesser than the Gunship at all.
At worst the Chieftain is equal to, but as I see it is currently better than the Gunship.
It has less hardpoints, smaller cap, and can't carry a fighter. I'm not sure that makes it better.
Firepower is arguable as the two central mediums on the Gunship always had bad elevation having limited or fixed options, and the lack of maneuverability limits its use to a skilled FA-off pilot usually.
Prior to engineering, this was a potential valid complaint; post engineering, the gunship is maneuverable, has an abundance of (importantly; usable) power, has 3 class 4 military slots and can carry a fighter.
The Chieftain's weapon loadout placement is borderline idealic for fixed or gimballed and with its outlandish maneuverability it is far superior to maintain time on target - the overall damage potential in a fight is leaps ahead with its speed.
We will see once it's live; the hardpoint placement on gunship allows for fixed and the grouping is still quite reasonable. If you are going to refer to gimbals on Chieftain, then gimbals on gunship mostly solve the class 2 hardpoint placement. The class 7 distributor on gunship means, even engineered, it can reliably power all hardpoints
simultaneously.
Something my type-10 now struggles with. Between the small cap, and placement, and the class 3's not deploying properly on the upper mounts, it's damage output has been severely constrained. I do find it a tad funny the chieftain has the same size cap as type-10 though, with nearly half the harpoints! Oh frontier..
However, to be fair to frontier, I
do like the setup for Chieftain, it should be quite good. But we'll know soon enough.
Outside the loss of Fighter damage - which is situational or limited depending on opponents - the Chieftain's jump range with speed is making it look like a much better alternative.
Fighters have extremely high damage output, and increase the total damage output, that for a gunship is already considerable given the combination of hardpoints and capacitor. A fighter also has considerable closure rate, and it can chase down anything attempting to escape.
Unless the Chieftain's shield remains weaker than the Gunship there will be very little to argue that it is any capacity weaker than the Gunship at all right now.
This is wishful thinking; I tend to think this is a good option for FAS pilots, actually. As that's a far more relevant comparison (similar agility, damage output, capacitor and lack of fighter).
But gunship? lol, no. Just no.