N54: Is port injection safe now or will it still be a risk to my car?

I'm currently considering port injection. I've read in some old threads about there being no way for the DME to stop the PI from spraying fuel when safety conditions occur, causing things to go kaboom. Does PI on N54 now have a way of implementing proper safety or is PI still a risk?

Also will port injection negatively effect my gas mileage when just putting around town? The majority of my driving is inner-city.

Thanks