hi guys,i read through whole thread,could not find comparison between sb600 & sb700 & sb900.

I want to buy a flash gun,maybe sb900 or sb700.but budget reason,i could not reach sb900.so thinking sb700.
after read some website and some comparison,few aspect i would like to know and that concern me is the GN and flash zoom of sb700 is lower than sb900.In term of flash power, sb900 is of course stronger than sb700.

If comparing sb600 and sb700,
sb600 is cheaper than sb700 ,sb600 spec states tat sb600 GN is higher than sb700 but does that really the matter?how about the flash power of sb600 and sb700


If you have any experience or advice on these 3 flashgun,please voice your opinion.thanks