To be honest, most systems will be quite reliable. After a significant mileage, injectors will need to be removed and cleaned, but don't require any periodic checks. Many faults attributed to FI / engine management system faults are often due simply to the usual wiring faults (loose / corroded terminals, broken / chafed wires etc) - its important when fault-finding these systems that you don't go overlooking the basics. For example, a system may give a fault code relating to a particular component (eg code 34 "O2 sensor faulty"). Many people will assume the sensor to be faulty, buy a new one, and have the same problem - because the wiring to it is damaged and the ECU can't get a signal. The signals in these systems are tiny, and it doesn't take much to upset them and cause a problem.
I've always taken the view that if I don't understand whats going on underneath, I'll take some time to find out - maybe it'd be worth buying a couple of books or looking for a college course to get clued up on these engine management / FI systems? You'll certainly learn something from it, if you do it through college then you'll make some new mates, you might get a couple of beers if you can help your mates having trouble with their machines, and you might just enjoy it - or indeed, you may even be able to find a job or carve out a new career with it if you're so inclined.