Exactly -- that is what is on the Yamaha website specs, as well, though there are some differences in the way the website lists the voices for the SX700 and 900. Now, 850 (voices) + 43 (drums/SFX) + 480 (XG) equals 1373 total voices, which is more than what is listed for the SX700 and almost as much as the SX900 on Yamaha's website, which is why I was wondering if it was some sort of misprint, with the 480 XG voices actually being part of the 850 main voices totaled in the spec. Because, on Yamaha's website, when you look up the specs of the SX600, it brings up a chart giving you the specs of the SX600, 700, and 900, but with the number of voices listed for the SX700 and 900, it does NOT list the 480 XG voices separately, which is why I thought they were part of the totals listed for those keyboards. But for the SX600, it DOES list the 480 XG separately, like I stated above. So, if there is a misprint in that chart, maybe it is leaving out the 480 XG voices of the SX700 and 900, which would then make their voice totals much higher.
But yes, the DGX-670 has clearly moved an order of magnitude ahead, with the style creator, additional voices, full XG implementation (the DGX-660 only has XGLite, like the E400 series), 16 track sequencer, hundreds of DSP effects, and 4-variation styles. That's why I was wondering how much of this might rub off on the E473. Remember, the DGX-670 is brand new, like the E473 will be. So a more apples-to-apples comparison based on what we already know would be the DGX-660 to the E453/463, which is where you can clearly see a similarity -- similar number of voices and styles (in fact, the E453/463 have more voices), 6 track sequencer, 2-variation styles, XGLite, and 32 registrations.
Of course, the DGX-660 has certain advanced features not found on the E453/463 -- obviously, the more advanced piano features, but also more polyphony, more DSP effects, more memory for the sequencer, and more auto-accompaniment features. And now, the DGX-670 has taken a step toward the more advanced arrangers. For example, I think the reason that you don't see in the specs how many banks of registrations are available is that it appears to be more of a memory-file system, and therefore dependent on available storage, rather than just allotting a fixed number of banks of registrations, like on the E453/463 and DGX-660. This is an example of a feature that I would not expect to carry over to the E473.
But maybe we'll at least get more banks of registrations, some improvement in the sequencer, and MAYBE 4-variation styles. I think improvements like this could be implemented without cutting into sales of the SX600, which would still have a more advanced sound engine, more sounds and styles, full XG instead of XGLite, more onboard speaker/amp power, more advanced style options, more registrations, a better sequencer, multi-pads, and the like.