Replace just one CV joint?

I recently replaced all four rubber CV boots on my 325i, repacked them with grease, and they seem to be holding up fine. During the installation, I decided to leave the axles inserted in their splines in the rear trailing arms because removal is pretty likely to mess up the rear wheel bearings and removing the axels completely is really not necessary. I simply removed the six or so bolts holding the inner CV joints to the output shafts of the differential and lowered the axle enough to remove both boots. On this particular car, you must first remove the inner CV joint to get to the outer CV boot. When trying to remove the press fit collar attaching the inner CV boot to the CV joint, the CV joint fell apart and all the ball bearings fell out onto my concrete floor. Bad news. I somehow managed to get the thing back together, but since I couldn't match the ball bearings to their original slots, the CV joint is pretty "clicky" when slowly pulling away from a stop (in forward and reverse).

So the question: Is it OK to replace just one CV joint (the inner) on the axle? The outer CV joint is welded to the axle, so replacing it requires buying a new axle but it doesn't seem to be making noise. Will a new inner CV joint cause the old outer CV joint to prematurely fail? I know I'm not the only car geek on Answers.

I ordered a new CV joint because of circumstances I won't go into at this point -- I just want to know if it's worth it to install the new joint or if I should pay the 15+ percent restocking fee and return it.