DelboyTurbo Decent ECU's have barometric pressure correction built-in which answers your sea-level point..

Most modern turbocharged cars use the MAF for all the base fuel map.. contrary to popular belief, n/a cars with MAF's only tend to use them on certain part-throttle areas of the map..

MAP is handy sometimes because you instantly know if you have a problem with the car (when you stick your wide-band on).. With MAF, it's tricky because if for some reason your car isn't flowing as much air, it'll still be fuelling right but you'll be down on power..

Horses for courses really..