Thanks for the further info.
I already possess an E-visitor sub class 651 which I used earlier this year and which doesn't expire until August 2017. There are no NFS on this visa. As regular visitors to Oz (3 times a year) I / we have never had any issues with re-entry. My partner also used a 651 this year due to the expiry of her PRV. This had no impact on her PRV renewal.
We wouldn't have any issues with an PV application offshore if the RRV had a 5 year timeline but the revised 12 months timeline is a very narrow time window to pack up your life , businesses, house etc. and with processing time of 15 months plus here in the UK i have no desire to live apart from my fiancee.
Interestingly if i had been questioned on our last visit time I would be have been honest and advised that we were visiting family as well as looking at homes and determining potential areas to live. To an extent that's exactly what we will be doing for the first 2 months or so next year the only difference being we plan this time to settle and whilst this is 99% certain we have to be realistic that there is a very minute chance that we come back hence why we will have returned flights booked. (No brainer given that from the UK the return tickets almost identical in price to one way flights).