But that does not take into account that while luffy was indeed tired from fighting, doflamingo had been involved in multiple fights and his insides were held together because of the makeshift stitching he did after law's final attack. Can you imagine how luffy's gear 4 would have performed against doflamingo if doflamingo hadn't been in such poor shape? The difference between luffy and doflamingo was immense even with gear 4 taken in consideration.
Well DD himself acknowledged Luffy was faster even before using Gear 4. Honestly, I disagree that there's a large gap between DD and Luffy. It simply doesn't follow what we've seen. Luffy needed 41 minutes of Gear 4 to defeat DD. He ran out of haki at 40 but what if Luffy hadn't been fighting and using haki prior to that? Even the time spent tanking Bellamy's attacks to save his pride instead of simply knocking him out involved him using haki.
This is just reminiscent of Luffy vs Lucci tbh. Lucci was leagues out of luffy's level when they first met. With Gear 2, Luffy closed the gap reasonably. With Gear 3, Luffy smashed him out of the water. Both situations involved the initially superior opponent being forced on the defensive. Luffy spent ages running around and using haki as well as his gears pretty much every time. Imagine if he and DD tangled while fresh and Luffy started out with Gear 4. You'd have him smashing DD about and in the worst case scenario, he'd run out of time before he can defeat DD but would've done more severe damage on DD. Enough for it to be considered a close battle.
Saying he barely felt the attack is perhaps a tad much considering he made the point that he was up against haki users. And even then, marco seemed to be in worst condition that akainu even when considering WB's attacks against him. Marco had been fighting longer as encountered multiple fighters including admirals. The war as a whole placed the WB pirates at a handicap considering they were the ones attacking a heavily fortified and prepared fortress.
Well Akainu did say it was a bother. It's manga speak for something more annoying/in the way than effective. Not sure how Marco was in worse condition. Marco got some kizaru lasers but Akainu tangled with WB for most of the time and was on the receiving end of WB's fury when Ace died. Sure Akainu seemed better off but that's because he's that much stronger. He fought a stronger opponent after all. Also, Akainu was never idle. He was always involved in a fight against one or multiple opponents. At the end, he's basically fighting Jinbei and WB's commanders on his own and he had then on the defensive.
Well the WB pirates might have been attacking a fortress but you could say the same for the marines. They had to guard against an avalanche of raging fighters. First it was WB then Luffy and his ID gang. Furthermore, they were supposed to ensure Ace wasn't saved.
Was garp placed at that level of strength? He was obviously pretty strong but the implication was that he cornered roger a few times. Which in context does not necessarily mean he was a match in terms of power. Not to mention that he has never done anything which suggest he is capable of feats of strength that could match the stuff we have seen from the likes of WB. Even sengoku who seems to be regarded similarly to garp did not really do anything even close to what WB did during the war. He did fight BB and his crew but even then it did not seem like he matched what we saw from WB... To compare the situation, imagine the strawhats being chased by smoker. Smoker is clearly weaker than luffy but if you add a battleship or two into the mix (which even now remain a force to be reckoned with) it's by no means impossible or a stretch for smoker to also corner luffy, crew and all. And then luffy escapes.
Well asides that, Garp has been stated to be Roger's rival as well. We even have WB acknowledging Garp and Sengoku while still referring to the likes of Akainu and Aokiji as brats. The point about Garp cornering Roger is a fair one as even I have considered that it doesn't indicate they are the same level of strength but Garp has also been referred to as Roger's rival. Even Roger says as much here:
That indicates that Garp was able to match his strength.