I have the Trio Sonatas disc of Alain's third (!) integral, and I like it very much. But maybe that's also because I'm somehow in love with the Schnitger organ of the Der Aa Kerk in Groningen (NL).
I also have a sampler of this Alain integral (issued last year or so) and I think it's quite good. Nevertheless, my feeling is that in general Alain is less impressive and more aloof compared to her second integral, which is still available. This second set was played on neo-baroque/classical organs. This also goes for her first integral which was recorded in the sixties, but alas has never been reissued on cd.
The Kibbie download is a great initiative, and in most cases I like Kibbie's no nonsense approach. The sound quality is good, IMO, and I do not mind about the variety of the instruments. In this way, it makes me think a little of the CPO integral by Gerhard Weinberger: some large organs, some small organs, some spatial recordings, some close miking. Yes, this makes for a mixed bag indeed, but it's nice to get to know these vintage beauties .... for FREE!

A very short thread about this subject can be found here:
http://www.magle.dk/music-forums/8407-james-kibbie-plays-bach.html
Btw, here are some performances on the Schnitger organ of the Groningen Der Aa Kerk, issued in 1990 by Lindenberg Books & Music. They went bankrupt in 2008 and now their productions are all officially OOP.
Bernard Winsemius (1945) plays Prelude & Fugue in A-minor BWV 569
http://www.mediafire.com/?d4t2quylmju
Stef Tuinstra (1954) plays Chorale
O Lamm Gottes, unschuldig (I think this is a keyboard setting of BWV 401)
http://www.mediafire.com/?y1mwj5yzomd
Winsemius: Trio Sonata in E-minor BWV 528
http://www.mediafire.com/?jdyynlztajn
Winsemius: Chorale Partita
Christ, der du bist der helle Tag BWV 766
http://www.mediafire.com/?ozd31zymomu
Tuinstra: Prelude & Fugue in D-minor BWV 539
http://www.mediafire.com/?2kfkqzoow1g
Enjoy!