[84LX89GT]

I've had 3 cars with T5's and they've all been fairly noisy. Once the miles rack up they only get noisier. It's a good idea to service the trans though becuase it only costs a TINY bit of money and time compared to any other service you could do.
I've heard that aftermarket shifters transmit more noise to the cabin because there isn't the soft rubber bushing in the shifter isolating it from the trans. I wouldn't worry about it until it gets either hard to shift, grinds or REALLY whines.
Also servicing the trans will give you an idea of how the internals are because there should be pretty much no silver flakes in the fluid (a tiny amount may be normal in a never serviced car with many miles) and copper flakes would indicate blocker ring wear which wouldn't be a concern either unless your car is having shifting problems.