They can feel ki but the plot requires the gaps to not be too big so you are forced to by the author's very intent to keep everything from Chaozus self destruct to Ten's Kikoho below Gohan's masenkos 2800. Obviously they aren't thinking these are 2x gaps in that case.
Why would Goku need a piercing weapon? The Majin charm doesn't give you any haxed durability or make you unkillable by conventional means.
SSJ2 Goku and Majin Vegeta were equal and took equal damage from their fight to the point where it was enough to awaken Majin Boo.
Videl broke...
But the in-universe characters aren't thinking "oh he has to be double my pl to tank this". They just know "woah he's strong, my best attack didn't even put a scratch on him". All that means is Chaozu's Self Destruct >> Scatter Shot.
While I agree that Nappa was 2x Kuririn's technique I don't think the characters necessarily have specific multipliers in their head. They can sense ki but they aren't numerical scouters and would necessarily know how strong you would have to be "to do this" or "do that".
Let's say Scatter...
Yeah but in those panels he says that Vegeta's pl is supposed to be the same as his. Cui is a bully, he is freaked out by Vegeta's pl being over 18k at all.
Cui didn't know Vegeta was surpressed but he probably thought Vegeta still hadn't fully recovered from his fight on Earth.
What special trait does Goku have? That is headcanon.
The only reason Nam was able to hurt Goku because he fucked up when spinning himself and ko'd himself. If Goku was smarter and less naive back then he would have won convincingly.
Seeing as Roshi was able to defeat Goku with a regular kick while both were equally tired because his legs were longer, yes. An attack like that from Roshi would probably fuck Goku up for a while.
Grade 3 could be a 10x multiplier over SSJ but it doesn't have to be. Either way it's impractical to use in battle due to the speed issue so it doesn't really matter.
Speaking of that, isn't this version of Goku a year ahead of main timeline Goku? Wouldn't that mean the ToP had already happened and the body Zamasu stole should be much stronger and capable of Ultra Instict?
Nothing changes. They were all getting stomped bad. Ten who is stronger than Yamcha got toyed with and survived his Kikoho with minimal damage, which is far more powerful than Sokidan.