No, but I think I should. I do however have a GFCI for my own and my family's protection. Ninety-five precent of electrocutions are ground-faults; it is a worthwhile investment and is required by US building codes now wherever water may be present. You can protect the whole circuit with one of these on the first outlet. You can also buy the plug-in type. I have one of these on my fishtank at work since the univeristy people will have 8 hemorages if I touch any of their wiring. The latter are actually more expensive.
The ground probe is a separate issue. I don't see how it could possibly hurt. Also, if significant current is leaking, this, in conjunction with a GFCI, will also help by tripping the circuit, thus alerting you to a problem needing correction.
I see no reason not to have one. At the very worst it is a waste of $10. Most things in this hobby waste a lot more.