Since this is not a regular rent situation, I do not ask for security deposits or last month's rent Your accumulating equity takes care of that, in my opinion. You may feel secure in making improvements to the property since you will own it some day. A renter cannot feel that way. But be sure to check with me first. And you will have a greater share of the upkeep than a normal rent situation would entail. I feel it is my obligation to provide you with a property that is right (everything works properly) to start with. Then it is your responsibility to keep it that way.
If you do not keep your part of the bargain, you will lose the downpayment plus any amount extra accumulated on it as this all non-refundable. That's sort of what you could give up. What I could give up of course is the chance to sell to the next guy who walks in and who wanted to pay cash (or whatever), only you got there before him. This has happened to me. And I lose any appreciation because I am selling in 2015 at 2013 prices. Everyone wants you to end up buying it and the more you have in your stash deposited with me, the greater the likelihood will be that you will complete the sale as we planned upon, which is what I really want. This system allows you to get a foot in the door and buys you time while letting you in right away.