You'll get far more value an bang for the buck with the Casio WK-3200/3700. The Casio will give you drawbars, voice editing, 76 keys with pitchbend and modulation, much better speakers, ability to load user samples such as user tones and user drum kit. The styles are a subjective issue. The sounds are also subjective, but personally I think the WK's are ahead of the 350/450. I used to own a PSR-550, and I dropped it for the Casio WK-3500. The newer 3200/3700 have improved sounds and twice the user sample memory (the 3500 sounds really good too and can be bought for around $330 on some sites) I'll be upgrading to the 3700 very soon.

Squeak