Please make sure you launch the X3 installer with the explicit Run As Administrator, as it give the install process more execution privileges than you get normally - even if the user account is an administrator.
X3d is quite stable, and lots of folks are pretty happy with it.
Many people in the forum have more than 1 set of recording software - lots of people do different tasks in different software. Nothing wrong with that. I wish I had that kind of money, though I would probably spend it on better reference monitors or food. :)
Bob Bone