The PIFR standards are the same as the full IR...(same tolerances on the flight test etc)...so it looks equivalent to the EIR...I don't know how many Australian pilots only have the enroute rating without any approach approvals but it would be interesting to hear how they get on....
I suspect most would at least get the ILS/LOC/DME and GPS arrival approvals as even dirt strips in the bush often have a published GPS procedure...so maybe there are very few with just the enroute rating...of course the traffic and radar situation is very different there...