my advise is to get nikon speedlight not because of the functions but more on the TTL.....i've used nissin di622 before and perhaps i am not good at it, the TTL isnt very accurate....nissin 866 is said to be super good but i still prefer to get a nikon one...

in regards of SB600...i am currently using it, why? coz its cheaper than sb900. its power its lower but its refresh rate is higher too. it is true that u cant possibly light up the whole hall and what u need is a good diffuser or a big bounce card to bounce the light lo....unless u wana fire ur flash XXX meters away....else, sb600 shud be sufficient...once u master it then maybe u wana upgrade it later? ive seen many who buy flash and store it in dry cabinet in the end...for me, i use my flash almost most of the time coz i like it

just my 2 cents....noob cents

why so susah? get sb-800 then kao tim..hehe..best of both worlds..not that much more than sb-600 =)