about Mb and quality of sounds, it is not as clear as it seems...
More Mb don't make always better sounds, it depends also of quantity of sounds, and Mbs for each sound.
For example, piano voices on PSR2000 and PSR1000 like the same (at the fact, both demos are the same, and sound exactly the same with an external amplifier), but 2000 has 16 Mb and 1000 has 8. But 2000 has more sounds.
Perhaps I don't say well, and piano voice on PSR2000 is better than PSR1000. ¿What do you think? For my ears, piano voice from 740 is the same that 2000, also.