....Son. When the Biju were only in V2, Kakashi and Gai were holding back to measure their powers (Stated by Kakashi). Then they went full BM, and Gai's first course of action would of been going straight into the 8th gate. Your point holds no weight, and doesn't even strengthen the notion that you suggest. Gai isn't going to go soft against 6 Akatsuki members from the start, and put himself in an even more disadvantage when they set up. He has the necessary speed to make the first strike, and it might as well be a big one.
Match ups are match ups, but it doesn't change the fact that they're portrayed and displayed by feats on different levels. Obito, Nagato, Itachi, and Kisame are simply on a whole other level then these guys. I guess Sasori isn't overall stronger then Chiyo and Sakura, because, you know, it's all about match ups.
The first use of Hirudora exploded on impact of Kisame, it didn't push him back. The one used on Madara pushed him away, yet the blast radius was seen directly behind Obito [
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], whom was nowhere near Madara the next time we saw him. The only thing inconsistent was the lack of aftermath shown the second time, but that doesn't take anything away from it's destructive power.
We already seen how fast and far Gai
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in the 6th gate, let alone the 7th. Then with the boost of his turtle summon (which Deidara knows nothing about, nor should expect) Gai can jump even twice as high. That should easily get him at least relatively close to Deidara, where a large scale AoE of Morning Peacock [
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] should knock Deidara out of the sky, where he proceeds to hulk smash. Only reason Akatsuki are winning is due to Zetsu, and Gai being outlasted. And even then it's a high-diff fight.