As a former CM who worked in bell services and valet dispatch at BW, (I ticketed all the bags that were stored at the bell desk), I feel confident and trust them. I do not hesitate to use bell services myself when staying at WDW. Much safer than keeping valuable items in a car.
There was never an accusation that something was missing while I was working (except a man who thought someone stole his Ray Bans ... that were on his head
)
Your only risk is a rogue bell services CM which I honestly never heard any stories about. There are so many other CMs around dropping off and retrieving bags, it would be pretty difficult to run off with electronics. Someone would
see you rummaging around the luggage. I'm not saying it couldn't happen, because anything can happen. But I really do trust them, even after being behind the scenes. I wouldn't think anyone would steal anything because it would be pretty obvious.
The bell services CMs store the bags, and get the heck back out to the stand so they can get back in rotation and get more tips. No one is really hanging around in the storage area - it would look odd to the others who are coming in and out. A loiterer would stand out.
I typically hide my electronics just in case (don't want it totally obvious they are there). If it makes you feel better, pack your electronics in the middle of your bag surrounded by clothes. It would look pretty funny for a CM to get caught emptying a guest's suitcase to find valuables
. And as pps have said, there's no harm in locking it to be extra careful.