What I took from the new Billboard article is that the band want to record more with a different producer. Lillywhite has engineered AB, JT, ATYCLB but hasn't produced since War, I believe.
My guess is that they recorded some good stuff with Thomas but there weren't enough great tracks to make the album they wanted to make.
If they have 7 or 8 really great tracks, maybe they want to try and get the other 3 or 4 to be just as great and sort of "hit the wall" during the previous recording sessions.
McGuniess was complimentiary of the bands work with Thomas in the article from u2.com, maybe they just felt like they needed one of the "old hands" in to help and that Lanois is certainly busy lately and Eno, well who knows, he's not really a guitar guy anyway.
I think its great news in terms of what the album is going to end up sounding like, but at this point, who the fuck knows when this album will come out?
Maybe the end result was that when it came time to select album tracks and finalize the album that they just weren't comfortable with an outsider like Thomas and wanted to turn back to a familiar ear.
I think ultimately it could make the album better, we won't know until more is said about the albums recording process (i.e. which songs that make the album were recorded when and with which producer etc.)
I think that the band have more songs in them and are wanting to explore those ideas rather than leave them on the drawing board like the last 3 albums.
One thing we should know is that U2 have gotten to the point where they will only release an album every 3 or 4 years. If it takes another 6 months or so of recording to make this album worth the wait, then I think it's a good thing.
Really there isnt much of a difference in releasing the album now or in 8 months other than appeasing us fans. But wouldn't we all rather wait for something special than to get an album that was not as good as it could have been?
One thing looks for certain. We will all have more time to save money for the tour.