If you've got the 463 it's likely pretty new? One suggestion if its still returnable is to get the PSR EW410. The speakers have got twice the power, and when you're dealing with so few watts to begin with, having twice as much gets you a big jump in volume and quality. Or, you could buy a used PSR EW400, which has the same speaker system, and it also has the advantage of having 76 keys instead of 61.
I've asked myself similar questions many times. I don't use the features of an arranger board but usually end up getting one 'cause some of them have really good onboard speakers, and they're usually pretty lightweight.
I had a Casio MZ-X500, sells for $1,100, and with 40 watts of power thru 4 speakers, it was a powerhouse. It gave me great, in my face stereo sound, and I supplemented it with a QSC K8.2, which added a bit more volume and a lot more bass. What a beautiful sound!
But now that that's been stolen, I've been using my Klipsch KMC3 speaker with a small keyboard. Bought it for $180 on Amazon, and what a boom box. It gives you stereo, has 2 2" speakers plus a 5 1/4" woofer. This bad boy puts out the volume, bass and quality, does a surprisingly good job for keyboards, super high fidelity (piano sounds great on it, the hardest sound to get right). It also is a BT speaker, so I use it for music during the day, and at night when I play music it gives me a rich, full sound. Highly recommended.