Charles T. Downey, writing on the ever-interesting Ionarts, briefly discusses Herreweghe's Bruckner recordings. To be blunt, I don't find the works particularly successful.In a sense, Herreweghe is doing with Bruckner what Boulez did with Wagner, circumventing a century of performance practice and move from massive density to more transparent clarity.
While I don't subscribe to the Bruckner-as-the-Wagnerian-symphonist idea, especially since the second part of Gustav Mahler's 8th symphony is as Wagnerian as anything Bruckner ever wrote, I think it's essential to understand Bruckner coming out of the tradition that informed Wagner. There is an emphasis on sound in Bruckner's works, and while the cathedrals of sound analogy is stale, I don't think it necessarily inapposite.
Boulez' Wagner is not necessarily universally beloved or even successful. Indeed, absent the Chéreau staging, I get the sense that it would join his 1970 Parsifal on the "for specialists only" rack in the metaphorical Wagner record shop. I like his Ring -- I like most Boulez interpretations, to the point of experiencing firsthand how different the live experience is from the occasionally anemic recordings -- but I would never say that his Ring is idiomatic. Indeed, it is the antithesis of idiomatic Wagner, thought out with an icy logicality and precision.
Herreweghe's Bruckner, on the other hand, doesn't strike me as a bold statement on Brucknerian idiom and modern practice. It certainly doesn't strike me as clearly delineated and thought out as Boulez' Wagner. Indeed, the recording of the 4th, which does seem to be a bit of a low point of Herreweghe's recordings to date, strikes me as a slapdash attack on Bruckner using some HIP practical and theoretical tools. Others have said this (maybe David Hurwitz, or maybe it was a message-board denizen: I'd give better attribution if I were inclined to track the comment down, but I want to make it clear I was not the ur-source), but just because Herreweghe likes Bruckner doesn't mean he's any good at conducting the works.
Listening to the recorded Bruckner corpus, one sees that there are a lot of ways to conduct the works. One can be as massive and powerful as Otto Klemperer's Köln 8th (1957), as expansive and slow as Reginald Goodall's BBC 9th (1974), or as dreamlike and spiritual as Herbert von Karajan's final Vienna 7th (1990). All of those conductors, in their own ways, however, understood the Brucknerian idiom and worked within those guidelines. To my mind, it is a little silly to apply period-performance techniques to the works of a composer who fell solidly in the "modern" musical age. There are no pressing questions about Bruckner performance like "With what shall we replace the Serpent?" or "What gives us the most authentic hautbois sound?" Bruckner knew the modern orchestra, so I don't see any need pretending that we're going to get any closer to Bruckner's world than Otto Klemperer, Wilhelm Furtwängler, or Bruno Walter did.
Of course, I have never been one to get too hung up on period-performance theory. A good performance of a given work knows no period and requires only the authenticity it gives itself.