You're missing the point of a different perspective... not everyone would spend money on styles. I don't really use the styles that come with an arranger and I absolutely never buy third-party styles... that's not how I stimulate my songwriting. None the less I answered your question as you phrased it. For me the hardware is the most important aspect - polyphony, sound quality, key action/feel, controller options, etc. And I am a pianist who often has to settle for second-rate piano substitutes. A CVP would not go in my living room, it would go in my studio and be a valuable asset to stimulate songwriting. Even if a CVP wasn't an option (room availability being a big factor for me), I would still spend all the money on music hardware.

BTW: if you do decide to spend $10K on musical equipment, spend it in South Carolina either this weekend or the weekend after Thanksgiving... those are tax exempt weekends designed for back-to-school shoppers and all music equipment, computers, software and accessories are tax-exempt. That would mean a savings of $600 on $10k.