The rent model won't work IMO, the premise of paying more rent...

The rent model won't work IMO, the premise of paying more rent (even if it is $2) and getting the benefit of a credit score (can't remeber a time in life this was ever required or important) is flacid at best. The 2016 consenus shows 2.2m privately renting in Aus and the ABS record an average of 2.6 person/home. I would derive from those stats that the high majority of the private rental market are couples or households of 2 families/friends. These aren't the type of people that will make use of paying a third party to pay their rent. Those demographics should be broken down further into age and employment status (which reduces addressable market share further) however you can see where the addressable market share is going, even with 10% of total private rental market(not addressable) using the service you're receiving c$5m RR.

I looked at this model years ago in the UK from a house-share bill splitting perspective and quickly realised it was too hard (you're acting as a third party between agency & tenant for a start which has legal obligations) and too little gain. When I did my initial research on friends, family, online surveys and randoms at events I was surprised at the negative reaction to paying even a small fee.
I transitioned to utility bill splitting model which can be profitable (look at Glide in the UK) but this is different to what Rent are doing. This model is based on utility bill splitting in house shares and does work, however I don't think the market in Aus is there for it.
I transitioned from this to another Utility bill model could have been highly profitable, however failed at final development stages for personal reasons and never had the energy to get started with it again. Pained me seeing the exact model on Dragons Den a few years ago.

That being said, Rent do have some traction and no doubt have the contacts. It looks like they have some of the right ideas but execution is everything in startup world. I hold as I'm interested to see where they get to.