What happens if a client cancels a milestone or otherwise simply doesn't hit "approved"? Machinist has my money, not me. I feel a lack of control, and I feel this isn't something I couldn't do with a single phone call and a cheque in the mail (or a payment on my own website). The price point is way too high for the service imho.

I don't even engage someone unless I believe they have the full amount of money available to pay me. And I don't start work without cold hard cash in my bank account. 50% up front, 50% on completion balances a client's commitment with a developer's commitment. Each party takes a risk in terms of time and money (big projects can usually be broken down into smaller 50/50 payments for milestones).

In terms of this service, I feel the developer is taking a bigger risk in terms of devoting time to a project that may or may not produce money, and in the meantime s/he has nothing to eat with.

I just don't understand the logic of paying someone to withhold my money from me when I can ask for real money up front, directly, for free.