how many people are using the new siemens injectors,closed loop set up on biggish power cars?

ive just got my rs500 up and running on 4 greys but need to get it to stu to get it set up one way or another.im feeling that the way to go is the above route,or could i stick with the greys and go closed loop,or just get it running right on the greys?im only asking on here as i keep mithering stu with different ideas so am looking to you guys for some advice so i can sum up the benefits/costs etc.

i wont be using the car too much so fuel economy isnt really an issue,but would like as much power as is reasonably possible.

im sure everyone now knows but here is my spec.
200 block,knife edged crank,low comp,multi layer head gasket,ported head,bd10 cams,verniers,bronze guides,double valve springs,air injectors,4 greys,t4,all cometic gaskets.l8 ecu with pectel board.but will have a standard board shortly.

the car is booked into stu on 26th april,so i need to know what i want by then