After I finally managed to download and read the Data List manual, I was able to examine the styles in the new PSRs. I made a comparison of the styles in the PSR 1000/2000 models with those in the 9000 by comparing published list of 9000 styles. For those who don't want to do all the work, below is a summary of the results. (I think I missed one of the 2000 styles in making this comparison so the list may not be perfect, but it will be pretty close.)

The following styles are available in the 9000, 2000, and 1000 PSRs:
(16Beat1*, 16Beat Ballad1, 16Beat Ballad2, 6/8 Blues, 6/8 March, 6/8 Slow Rock1, 60's R&Roll, 60's Rock1, 60's Rock2, 70's Disco1, 70's Disco2, 8Beat1, 8Beat2, 8Beat Adria, 8Beat Rock1, Acoustic Ballad, Amazing Gospel, Analog Ballad, Bebop, Beguine, Big Band Ballad, BigBand Shuffle1, Bluegrass1, Boogie1, Bossa Nova, Caribbean, Cat Groove, Cha Cha Cha, Christmas Waltz, Christnmas Swing, Club dance, Country 2/4, Country 8Beat1, Country 8Beat2, Country Ballad, Country Brothers, Country Pop1, Country Rock, Country Shuffle1, Country Swing1, Country Waltz, Cowboy Boogie, Croco Twist, Disco Chocolate, Disco Fox, Disco Hands, Disco Latin1, Disco Philly, Disco Samba, Dixieland, English Waltz, Fast Bossa, Foxtrot1, Funky Fusion, Guitar Serenade, German March1, Gospel Brothers, Guitar Pop, Gypsy Rumba, Gypsy Swing, Happy Reggae, Hard Rock, Hawaiian, Heart Beat, Hip Hop Pop, Hoedown, House Musik, Hully Gully, Jazz Ballad1, Jazz Rock, Jazz Waltz, Jive, Jumbo Reggae, Kool Shuffle, Limbo Rock, Love Song, Mambo1, Musette, Ober Polka, Ober Walzer, Off Beat, Organ Ballad, Organ Quickstep, Pasodoble1, Piano Ballad, Polka Pop1, Pop Ballad, Pop Bossa1, Pop Rumba, Pop Shuffle1, Quickstep, R & B, Ragtime1, Rock & Roll, Rock ChaCha, Rock Shuffle, Root Rock1, Rumba, Rumba Flamenca, Salsa, Samba, Saturday Night, Showtune, Slow & Easy, Slowfox1, Soul, Soul Beat, Soul Shuffle, Swing1, Swing2, Swing Fox, Swing Waltz, Tango1, Tarantella1, TechnoPolis, US March, Vienna Waltz.)
* Note: sometimes one or another model had several variants of a style and they are numbered 1, 2, 3 etc. If there is only one version, it has no number. To make the comparison, I renamed the single style "1" and assumed it was on both machines. For example, the 900 has 16Beat 1,2,3,and 4 while the 2000/1000 only have a single 16Beat style. I called that style 16Beat1 but it may or may not match any of the 4 styles currently in the 9000 16Beat series.)

The following styles are in the 9000 and 2000 -- but not the 1000:
(Bluegrass2, Bolero, Espagnole, German March2, Jig, Modern R&B, Pop Waltz, Singer Song Writer, Traditional Waltz, Twist.)

The following styles are in the new 2000/1000 -- but not in the 9000:
(16Beat Uptempo, 6/8 ModernEP, 6/8 Orchestral, 6/8 Slow Rock2, 6/8 Soul, 60's 8Beat, 60's GuitarPop, 70's Disco3, 8BeatModern, BigBand Fast1, BigBand Fast2, BigBand Mid1, BigBand Mid2, BigBand Mambo, BigBand Salsa, BigBand Shuffle2, Brazilian Samba, British Pop, Charleston, Childrens March, Club Latin, Country Pop2, DetroitPop1, DetroitPop2, Disco Funk, Disco Party, Euro Trance, Finger Pickin, Funky Disco, Garage1, Garage2, Hip Hop Groove, Hip Hop Light, Hip Shuffle, Ibiza, Jazz Club, Latin Disco, Modern Country Pop, Moonlight Ballad, Pop Shuffle2, Rock Ballad, Rock+HalfTime, Scottish Reel, Secret Service, Slow Bossa, Swing House, Tango2, TechnoParty, Tijuana, UK Pop, Unplugged, Band March*, Band Waltz*). (* 2000 only)

Note: there are a number of styles included on disc with the new PSR1000/2000 but those style names were not available in the Data List manual.