Changing to Syn oil should really be dependent on the miles on the car and how its been maintained. For ex: you do NOT want to change to syn oil if its at 120,000 miles and leaking. But IF the car has somewhat low miles, and regularly maintained, and you can afford the $$$ that comes with a syn oil change every 3-5000 miles *depending on driving habits* then id say itd be better to switch.
The syn oils tend to last longer, lubricate better, and most claim it will actually make the motors last longer. I personally have not gone back to using regular oil after the first use of Mobil1 syn... but when you drain the oil out of your 25,000 mile engine at 5000 miles and it looks like new Pennzoil 10w30... theres something there to
about with the change you did. Its like going from regular gas to premium, its usually cleaner, makes the engine run better, and its worth *to most* the slightly extra cost.
All in all, its up to you