I'm sure baggage theft goes on at most airports and hotels in the world at some times. I've been to the Phils 7 times and never had a problem with anything being stolen, but it's still wise to be careful and keep your baggage locked with a good quality padlock or combination lock.
I've taken a fair amount of surplus old electronics equipment out there (laptops, cameras, phones...etc) and never had a problem. If you're taking brand new boxed equipment you might have to declare itbut if it's second hand and as long as it's only one of each item, it shouldn't cause you a problem.
Be on your guard for helpful Police and Security guards looking for tips or souvenirs. they can spot a white man 100 yards away and will bend over backwards to help you, and will usually ask you for a tip at some point. It's at this point that I suddenly forget how to speak English (BTW, I've found it helps to tell them you are Norwegian, as it's a pretty safe bet they can't speak the lingo)