the -800 and -900 have artificially raised app/ref speeds for F30/F40 to provide for a lower body attitude. on the 700 the diff btw F30 and F40 is about 2kts as far as i remember (i usually fly the 800, only about twice a year the 700). on the 800 (and presummably also the 900) the diff btw F30 and F40 is 7kts. this added speed is supposed to keep your pitch down. check the FCTM. the body attitude on approach is 2.0° for 600/700, 1,4 for 800 and 0.9 for 900....get the idea?
from the Touchdown body attitude tables you can see that the 600/700 @F30 has about 6°-7° while the 900 only has 4-4,5°. also the 600/700 tailstrikes a 12, the 900 at 8 (T/O likewise).
not sure if mentioned in text, but obviously the longer models require a shallower flare.