@SpeedForceSpider: Its worth mentioning that this is the weakest form of Hirudegarn, easily defeated by Gotenks SSJ3 so yes his power is greater than Vegeta's but not at a ridiculous amount, he got easily! defeated by an Gotenks SSJ3, however Hirudegarn would be the worst example to make as he is an walking PIS machine, beating Gotenks SSJ3 in one hit, butchering Mystic Gohan but loses against Goku SSJ3 who took 4 hard punches in the face and did nothing :S DBZ plothole 158665 :). Again the battle of the Kai's needed to be sped up, hell after the battle was over the episode lasted for like 5 minutes before Kid Buu blew up the Earth so Grand Kai like the other Kai's have very little showings and Grand Kai wasn't even tested he simple got absorbed by Buu, we didn't seen him actual fighting Mega Buu like South did against Kid Buu. Your somewhat right about durability, Vegeta did absorbed a bit more hits than South but the simple fact remains South actually had the strenght to fight with Kid Buu whereas Vegeta absolutly could not do, he did hit Kid Buu (when he was knocked down by Kid Buu's headbutt going all mental and ****) and deliverd 4 punches and that was it. I'm beginning to sound like a broken record :) but yeah Vegeta ofcourse has better durability than South because lack of screentime, how South lost was complete BS with the whole neck kick thing that i explained in my previous post.
Lets say this, if South Kai had recieved 10 more minutes of screentime and ignoring the BS durability, and looking at the battle prior the neck kick and how well he did would you still think Vegeta>South?
In the beginning of the battle he hasen't had a drop of sweat on his forehead, was smiling, and charged Kid Buu head one, he should have far longer durability than what is shown.....aarrrhgg, again think about how stupid that was and so unreal, he did so well against Kid Buu and just one little Neck Kick and his entire body was broken and beaten up, arms/legs and he was bleeding from his head WTF! since when does is happen when you recieve and Kick to the Neck that your arms and legs get destroyed and Face mashed in, you saw how badly injured he was it makes no sense other than the fight needed to be wrapped up, similair in the DBZ movies. In the DBZ movies fighter shown far less durability than in the show because in the show they have longer screentime, think about it, Goku takes hits like an planet from opponents far more powerfull (Frieza before SSJ) than him but after a few kicks from Turles/Slug and he's half dead.
If we exactly take what was shown from the flashback then your right Vegeta should win because of a far greater durability, but i'm calling BS on that and i want to know if South had more screentime thus not suffering from BS durabillity like displayed alot in the movies, would your then still think Vegeta>South? taking into acount what South did shown, Grand Kai including.
I'm still not sure about where to put Grand Kai, its for me hard to imagine to put a character who lifes for only 3 minutes and put him at SSJ3 lvl, but i think its possible. He's either even or weaker than SSJ3 and i don't think he be stronger and if he was it would be minimum but...i don't know yet :) i gotta say i'm having fun debating with you i hope i'm not boring/irritating you with these wall of texts :) I've said before in the OP that this could be difficult because they only life for 1 episode but thats the fun of it :).