The firmware mod you mentioned is specifically flagged as not working on the international version, which is the one you will have.
I take your point about Wikipedia. If I were you, I'd keep the wireless switched on for occasional uses like Wikipedia, and off the rest of the time. That's mainly to conserve battery. I wouldn't be too bothered about Amazon knowing what I'm reading.
In fact, I don't have the choice as I have the US version of the Kindle and am outside US Whispernet range.