How abou this:
I was hooking up a reactor to the back of my old 28G Nano, well I hooked it all up except didn't hook up the return. I don't know why, but dummy me... I turned on the pump and started pumping salt water all over my feet, onto the floor and onto my power/controller bar... Well sparks flew, and I got out of the water real fast, unplugged the power bar but it was too late. I fried the $60 bar that fast, if my feet were in the water, I probably would of had a jolt of a lifetime or more.
So I run 2 GFCI's now for that reason... Another reason also:
I was trying to put electronic ballasts onto my old fixture that had magnetic ones... Well the GFCI kept tripping, so I thought that maybe I had too much on the line now, so I got an extension and plugged it in somewhere else. Well When I plugged the electronic ballast into the fixture and then to the wall, I had a small nuclear explosion and blew the left side of my light...
Again, the GFCI was indicating a problem... So I listen to them when they don't want to stay active.
I hope this helps, and for 30 bucks or so, it is well worth it
Lastly, do you want to burn your home down, I have seen pic's of such a thing.