You headed this up PIFR vs CIR. No-one seems to have answered that.
Hmmm - could have sworn I did! Private or commercial, get a CIR and learn to fly to fly in the poo with confidence! Once you have done that - get the PIFR issued to give you a bit more flexability with recency if you are on private ops.
Just to clarify, if I already hold a CIR that is both current and recent, is getting a PIFR simply a paperwork exercise (with a small cost now doubt)? Do I need to do an additional test flight to get the rating?
Get the form off the CASA website, fill it in, pay the fee, wait for them to send you the new bit of paper for your licence. Simple as that!
I have held at one time a MECIR, I now just want to fly IFR on PVT ops. Can I do a renewal (initial issue flight test) for CIR on SE and the get the PIFR endorsed in my log book or how does it work ? ?
You will need to do the equivalent of an initial issue (ie fly all the aids you require in the aeroplane) in a SE aeroplane, then get the ATO to issue the PIFR as well as the CIR - or get the CIR and do as above!
For about four renewals in a row I asked my ATO to do the paperwork for the PIFR as well - and for four renewals in a row he ignored me! Doesn't believe in PIFR - so I paid the fee and sent the form to CASA.
Dr 
PS: Same advice given here as I gave to Jaba. For some strange reason, he listened! Got the CIR for private ops. I honestly believe that he is a more confident, competent, safer IFR pilot as a result. I haven't flown IFR with him cause I won't get in a Retard Vehicle (
), but I have it on good authority that he does it well! He flys some pretty hard-core IFR in that mobile Dick Smith shop he calls an aeroplane!