Ok, now I'm not trying to go against the wise expertise of the folks here on this thread, but I know 3 folks with Boxsters with over 150k miles on their original clutch, and one with over 225k miles on their original clutch. As I said before, I also was led to believe that my clutch needed replacement at 30k (because they said my clutch was heavy), but am now at 62k with the same clutch, so I just can't believe that it is normal for a clutch to fail on these Boxsters at less than 50k miles, unless you are abusing the clutch.
Also, I have read of at least 2 threads on this board whereby owners stated specifically that their clutch was starting to slip, and so can't believe that the Sachs clutch in the Boxster fails differently than they do in all other cars. Here's a thread on how a guy experienced clutch slip at 92k miles on his Boxster:
Problem with acceleration
Perhaps it is a good idea for the OP to change his clutch now if he is experiencing difficult shifts, but I really don't think he should change it just because he's at around 50k in miles, absent any symptoms.