the only issue with that link is the 2.1 is not on there. I have the 2.1 file if you need it, just let me know and I will post the file here. It is usually in my article section, but that part of the site broke when we upgraded the forum, and I'm still working on getting it working.
FYI, 2.1 is the only one that I would suggest if you have little experience flying. If you are good at flying helicopters (CCPM), then go for 3.1, but make sure to pop it off the ground fast, as it wants to tip over if you spin up the head to full speed (or just regular lift-off speed). So go about half way on the spool up, and go full collective to get it off the ground.
And save up for a better gyro, the 3GX is WAY out dated.