Yeah, Vai's playing of EVH's stuff has something of an odd feel to it. Bits of it sound more forced than when Eddie plays them.
Anyway, to say something I should have said before, if you can, try and find LA and San Francisco 1986 shows (San Fran is better, IMO), as those are two of the better sounding Eat 'Em And Smile shows. For the Skyscraper shows, look up Tokyo and Osaka 1988, as, again, both are among the best from that tour (One of those is better than the other, but I can't remember which
If it helps, some of the songs were only played on certain tours. Unchained, Pretty Woman, and (I think) Everybody Wants Some were only played on the Eat 'Em And Smile Tour. On Fire was played often then, but only rarely on the Skyscraper tour. Hot For Teacher and You Really Got Me were only played on Skyscraper tour, while the rest (Panama, Jump, and Ice Cream Man) were played at pretty much every show.