Is it safe to remove PC (polycarbonate) arms from minfigures?
The clear PC arms are more brittle, however you should be able to replace them at least once, since the torso you are placing it into is ABS - so there is a bit of a give/flexibility on that side. 

One thing to be careful of, is when you take out the PC arms (and when you put them in a new torso), do not hold the arms by the hands! This will put pressure on the wrists and can make the more brittle PC plastic crack. Either hold the arms further up, or even better, take out the hands first, then the arms. Hope this helps.