Having a debate with a friend and he thinks the Su5 would make PUP competitive on the DD scene against other REMA DDs.
Short Answer: No, it won't.
Long Answer: There are some core design flaws with PUP (and by extension BST), and generally how the game works, that is preventing PUP from competing on even footing with other damage dealers in a typical endgame setting (ex: Dyna[D], Omen, HELMS).
For starters, buff mechanics -- BRD songs have no effect on our pets, while a select number of COR rolls buff ONLY pets, and the only GEO bubbles pets can take advantage of is debuff bubbles (so no double-stacking such as +attack and -defense). Buffing jobs have a limited amount of buffs they can apply, and have to select their buffs according to the group.
This naturally just leads to conflicts when you throw a PUP in a DD party with other jobs. If the party is melee centric, you end up with buffs to super power the master and your pet ends up falling way way behind. If the party is pet centric, you end up with a super buffed Automaton, and the master ends up being incapable of dealing damage themselves (either due to danger, lack of melee buffs, or both).
So there is no in-between... In an end-game setting, where you are competing against other jobs, you're either buffing only the master or you are buffing only the pet. DRG & SMN, the other pet jobs, circumvent this issue because DRG is heavily master-oriented with very little emphasis on their pet's damage output, while SMN is the opposite, and is heavily pet-oriented with no emphasis on the master's damage. BST's, the other hybrid pet job, feel our plight in full though...
The second major design issue, is Square's complete lack of ability or knowledge in creating proper hybrid pet armor sets and accessories. Both PUP and BST
desperately want to equip armor sets which enhances both the master and the pet equally, but no such equipment exists, and the equipment that does is woefully underwhelming. In order to even cap your automaton's haste, you need to make major sacrifices to the master's throughput in certain slots or vice-versa. Not to mention the current issue with weaponskill sets for the master and the pet also being completely separate, and the inability to gearswap effectively for your pet WS without hampering the masters damage or safety momentarily.
When you look at the Su5(C) fists in regards to what I wrote above, you should be able to see the problem. Path C has +Weaponskill damage and Automaton ability damage+, but there doesn't exist an instance where you need both of those
simultaneously. With the way the game works right now, you are better off buying 2 Su5's, using Path A(or B) when the master is heavily buffed, and using Path C when the Automaton is buffed or Overdriving.
So tl;dr: the concept of a truly hybrid pet job (PUP & BST), where the master and pet have a 100% output potency, is currently flawed, nearly impossible, and doesn't work with the way the game functions at the moment, or with the equipment available. So until these core design issues are addressed, PUP is always going to be held back, especially compared to other super buffed REMA DD who don't need to make such sacrifices.
It isn't all doom and gloom though! PUP has lots of strengths it can lean into to make it a valuable party slot, particularly it's support-free tanking capability, respectable (but not top) damage throughput, solo ability, and safety pet strats. I just think pretending PUP can compete pound-for-pound in raw damage to other DD jobs is simply unrealistic.