@Watch-man:
Meaning that without those Biscuit soldiers Cracker was not enough to overpower Luffy who was using Gear 2nd and 3rd at best(it was indicated that he didnt used G4 beside start and end of this fight).
Also Luffys haki was strong enough to block plenty of Cracker piercing attacks at start of a fight, only time Luffy was cut was when his arm was streched and Cracker had swinged his sword from close gripping it both hands.
To me it was clear that in direct combat against Gear Fourth, Cracker was weaker than Luffy. They clashed and Luffy won a clash of power.
Cracker when it comes to his offensive powers was weaker than Luffy in Gear Fourth, when he was in his main armor using CoA hardening on his sword it was still not enough to push Luffy back. Then he started to make armors that were enough to slow Luffy down so in general Cracker offensive was weaker than Luffys offensive but his defensive ability was higher than Luffys attack power when using even attacks like G4 gattling(that I see as weaker than Kong Gun as I see Red Hawk being stronger attack than Hawk Gattling).
Also I think you are not correct in thinking that in Tankman Luffys haki is somehow stronger than in his base form or Boundman - it is same Haki but with mixed use - mixed with Luffys DF ability. We seen Luffy blocking tip of Cracker sword with his haki when Luffy was in Boundman, it was same as when Luffy stopped his sword in Tankman mode.
Can you show me if it specifically indicated he only used G4 at the beginning and end? I don't remember honestly because it feels like ages. I only remember Cracker saying fight, eat, run, etc.
Crackers haki and offensive was significantly different between his actual body and his biscuit. In his biscuit form, his CoA was overwhelming Luffys, but not enough to completely pierce him or even match G4. In his actual body, he was capable of piercing Luffys G4 arm, something even Doflamingo couldn't do with a haki imbued 'Athlete' attack, only for Luffy to note how a 'crappy' attack like that wouldn't work.
Yes it was stretched, but Luffy was also in a vulnerable position following his initial miss on Doflamingo (albeit not stretched). Was there any point where Doflamingo was shown to significantly cut/bypass Luffys G4 CoA like Cracker? I don't remember either, THAT was definitely ages ago. I don't think it would be completely accurate that downplay that moment to a significant degree, because (assuming Doflamingo didn't pierce it) no one yet has shown to break his CoA in G4.
They clashed in direct combat with Crackers 'Honey Pretzel' attack, when Luffy when into Tank 'Full' mode. We haven't seen its usage in any other fight other than this one, so it's hard to analyze it. But, the fact still remains that although Luffys arm was stretched, Cracker was still capable of cutting a decent amount into his arm G4 CoA heavy arm in Boundman. For him to tank, absorb, and reflect Crackers named attack, there must have been some highly significant difference.
G4 in general is already a mix of Luffys DF ability and Haki, Doflamingo himself stated that already fighting Boundman. Even if the difference is simply a different allocation of where to concentrate his CoA, the mere fact still remains that the difference itself was large enough to compensate for Crackers named attack VS. when he got cut earlier.
And again, his main armor and his actual body CoA hardening were shown to be significantly different. Where the main armor, or biscuits were shown to only tank about 2 hits of a Kong Gun, uncapable of pushing back, his main body itself was capable of penetrating.
You also just can't take away his Biscuit soldiers, they are after all his combat style and a part of his DF abilities. It's not the same as taking away Judges 'pawns' during Sanjis fight with him (which I still believe to this day would have been a Judge KO).