Good point Tacpot and one which I forgot to mention!
If anyone is worried about not having an FAA PPL but intending to progress then dont worry! Once you take the FAA CPL then that becomes a licence in its own right - you dont need to have previously held a full FAA PPL in order to take the CPL exams and flight test - an ICAO one will do which will allow you to obtain a restricted FAA PPL for the purpose of progressing up the ladder.
As stated before then is nothing to stop you adding IR, Complex, High Performance endorsements, etc to a restricted licence. To get round the night issue then you will have to undergo the JAA Night course and get the signoff which will then lift the night flying restriction on your FAA licence, you wont have to apply for a new FAA licence when you complete the course as it just refers to your JAA licence number.
If you are intending to stay pottering about on a PPL then its probably worth getting the full FAA PPL, especially as medical requirements arent as stringent as the JAA PPL (Class III only required).