I happen to think the Saiyuki dub is extremely well done. Ok, before you so-called anime 'purists' who only insist on subs start hurling sharp objects at me, hear me out: It is extraordinarily hard to "match" the talent of Japanese seiyuu. Dubbing productions-good ones anyway-try to find English speaking talent to complement the Japanese speaking counterpart. Thankfully, anime dubs have improved in recent years. (Some notable mentions: Cowboy Bebop, Hellsing) In case you are wondering "why have dubs in the first place, just read the subtitles, dammit," remember, not everyone can read as fast as some. I, for one, can-but some whose English reading skills are not up to par (my anime-lovin' friends who have English as a second language come to mind) appreciate the dubs. Plus if a dub is extremely well done like Saiyuki, I can love both sub and dub. And I do.
Don't complain about dubs just because you think it'll be "cool" as an otaku to do so. That sounds as narrow-minded as the people, who consider Japanese anime as kiddie cartoons. Yea, you know how that can be annoying. Getting back on track here, I once read that a reviewer would not even consider the Saiyuki dub only because "no American voice actor could act better than Toshihiko Seki!" Although I worship the work of Seki-sama, I think David Matranga does a splendid job as Sanzo-his voice is awsome. And Illich, the voice actor for Gojyo was perfect!( In fact I like the voice actors so much, I now follow most of their work and go to conventions to see them regularly-oh yes, they know who I am!) I have heard some say that English voice actors cannot act. What the heck does that even mean or imply? It does not matter where you are from, if you can't act you can't act....that goes for Japan or the US.
However, why do some dubs fall flat? Bad casting, bad acting, changing the script unnecessarily (think of the name changes in Sailor Moon) and lotsa edits and cuts. (Tenchi Muyo suffered this one when broadcasted on Cartoon Network) Saiyuki, thankfully, does not have any of these things. In fact, the ADV production includes a cultural notes sections, so that we may even learn a little something about the legends, history and background that gives rise to this beloved series. Just "open up your mind". A little bit, anyway.
I'm not completley trying to change someone's point of view- In fact there was once a time where I would only watch Subtitled shows. It wasn't because I thought it would be cool if I was a "purist", It was because I respected the acotrs like Seki-sama and everything he did. But, if you learn to be a little more easy going-like I was-You will see that it's not that bad. So try it, give Dub's a chance!