Haven't played with the organ flutes much, except to remember that they sound good.
However, you can download the manual for the PSR740 from Yamaha's website. It takes a while, but then you'll have it on your computer to read or print out as you choose.
There are a number of improvements over the 730. Just a few are: increased polyphony, 4 variations per style, simple endings (great!), vocal harmony, better e.q. and dsp's, better sounds, including Sweet voices, grouping of styles and voices that makes them easier to find, tap tempo, and better, more logical layout.
Sell your 730 to some little old lady and get the new one!