Nice work on this! I'm definitely tempted to pull the files out and give it a shot when I get a chance. I wish the vocal stayed in the center for the whole track, but moving it to the mains would definitely add some consistency.
One of the most fun aspects of this hobby IMO is the speculation about why engineers make the often baffling choices they do on these multichannel remixes. Usually we don't get the answers, but in this case we have that
very in-depth interview with Neil Dorfsman where he admits he was going for a conservative style, to the point where he even upmixed elements from the stereo CD! He even states that he feels Oasis' dense "wall of sound" recording style isn't well suited for surround sound, so I suppose you could say there was an anti-surround bias going against this one.
While there may be some technical problems on top of it all (such as the vocals awkwardly switching speakers in "Wonderwall"), I think most of the weirdness/disappointment associated with this one
can be chalked up to the mix philosophy. I'm not intimately familiar with this recording, but I think it's got enough elements to make a more discrete and logical surround mix than what we ended up getting.
Honestly, more than a few of these early 5.1's from Sony sound like rushed afterthoughts. A lot of the stuff in that article just sounds like a repeat of what they were doing in the days of quad- surround rushed to the market, mixes completed in just a few days, the band not being informed, etc. The big difference being that the crappy matrixed vinyl system forced them to do crazy discrete four-corner quad, whereas the fully discrete SACD format allowed them to get away with submitting these boring conservative surround mixes.