About the pacing - in short, I really liked every bit of DB, so not once I thought to myself "Man, this is kinda slow" or something. I see your point, I get that the pacing isn't good all things considered but as I pointed at my post, nothing watching Z with guide can't fix. I skipped Garlic Jr. and Otherworld tournament and it was fine.
If friend came up to me and said he wanted to give DB a chance, I would get him to watch original DB first and see whether he REALLY liked it or just enjoyed it and using that I would direct him to either Z, Z w/o fillers or maybe Kai.
About the voices, I'm not a dubfag so I watched the entire show in japanese so I can't judge really. Yes, the scene you linked the Kai is better but I saw Saiyan saga Goku vs Vegeta fight dubbed and I liked the Z version better, I find the lines in it a bit more memorable. Frieza voice is horrible though, If the person cannot handle subs, first he's a big fag, but I would probably get him to watch Kai.
The soundtrack is a total subjective matter. Despite listening to the whole Faulconer OST and thinking it was aight, in my opinion it doesn't fit DB in the slightest. Kikuchi's big orchestral score is definitely way to go. Every song is a banger and fits the large-scale fights perfectly. Kai really fucking failed head first by replacing it. I get when somebody has nostalgia boner for Faulconer though.
So in the end I think it depends on the person you're recommending DB to, but since I think Z and Kai have so much different atmospheres, Z is way to go. Maybe JPN = Z Eng = Kai