Not surprised RM's are not mentioned much on this forum, most brokers keep away from them, increasing ASIC requirements, most lenders require SEQUAL membership for brokers, small loan sizes (average around $60k but have done many for smaller amounts) and they take time to make sure the clients understand the possible outcomes, beneficiaries considered etc.
However I have also done RM's for seniors with considerable equity who want to help their kids have a start in the property market, so rather than waiting for death to pass wealth on, they can use a RM.
As others have said, in essence just like a normal mortgage over a property except that no repayments need to be made until a defined event, such as death, sale etc. It is possible that it could be in place for 30 years or longer. Repayments can be made and beneficiaries may consider making these to keep the loan size down. For the CBA product, it is a capitalising LOC essentially, although it is the most expensive and has monthly fees.
Some lenders have a increasing sliding scale of LVR based on age, but not all do, Bankwest for instance has one limit regardless of age at 25% LVR. All lenders require legal advice, some require financial advice also.
The Bendigo branded product is a deferred real estate sale, it is not offered in all areas, very restrictive in post codes and property types as it is based on a share of the final sale price. In a strong property market, it will be far more expensive than a RM will.
Reasons are varied why seniors chose this option, for many it is just to supplement their pension and have a quality of life, some use it for their Bucket List, a visit to the old country one last time while they still can. Others use it for travel, upgrades to their home, replace a car and to assist children. I have not come across a senior whose kids have objected to their parents enjoying a quality of life on retirement, the sentiment loud and clear, 'it is your money, enjoy life'. They may only need $20k or $30k, a RM is an option to consider if the only alternative is to sell and downsize.
The risks are the compounding interest over time but legislation is such that the no negative equity guarantee is that the debt will never be more than the property value itself. Lenders are not in this game to lose money, hence the low LVR's offered generally based on age. With the lack of lender competition, they charge like wounded bulls on establishment fees and higher interest rates, best at the moment is 6.70%.
Hope that helps.