It is a bit of a surprise that Yamaha deleted the music database for the E463, considering how common that feature (or something similar to it) is throughout the line of Yamaha keyboards. Does a keyboard really need 70 preset songs? A keyboard is for playing music, not listening to prerecorded music. I would think that it would've been better to reduce the number of preset songs to allow room for the music database. As I recall, when the E443 came out, they reduced the number of preset songs from 100 (in the E433) to about 30, presumably to "make room" for new-at-the-time features like audio-in and tunable scales.
But, as I rarely use styles except for the drums, the lack of the music database feature would in no way be a deal-breaker for me. I'm debating on whether it's time to upgrade, or whether I'll kick the can down the road two more years and wait for the E473, since there aren't any really major changes to the E463 from the E453, other than the sampling and audio recording.
So... from my E433 to the E463, the main things I'd get are...
A few more sounds and styles and DJ patterns
Tunable scales
Audio in
DSP effects
USB audio out to computer
48 note polyphony
Sampling
Additional knob effects for the background
Audio recording to USB
Out of all those, I would probably use the DSP effects, 48 note polyphony, and sampling feature the most. And maybe the ability to add reverb to the drums of the style would be nice.
But otherwise, things like the 6-track sequencer, the 32 registration memories, the operation of the rhythm section (styles and drum fills), the sustain pedal (still no split voice sustain), overall voice quality (which has always been excellent), and operation of synth features like the filter and envelope generator remain essentially identical to the E433.