The P8 you can run closed loop as standard,also has the facility to run a wasted spark set up,it already has the driver board installed in the P8 but you will still need ignition amp,leads etc obviously.P8 is a faster processing/moitoring ecu,cleverer than the L8 but P8 are renown to have problems from time to time.I'm no expert just what I have picked up on as I looked into running a P8 on my car,I have L8 at the moment.
Your best bet is speak to your tuner/mapper as a few top tuners would prefer to use the L8 set up.I hope this helps.

Thanks.Lee.