All three of the firms you mention will be a 3rd party processor. They will hold the funds, sign every document, cut every check, and receive every deposit. If by investing in real estate, you mean purchasing a plot of land and sitting on it, this business model may serve you well.
If you are considering investing in rental property, that is an asset type that is not well served by a 3rd party custodian. The paperwork, processing delays and per-transaction fees will become a real barrier to success and potentially to compliance. If a water heater breaks, will you be able to find a contractor willing to wait 7-10 days to receive a check from your IRA?
I would suggest you evaluate programs that offer checkbook control such as the IRA LLC or Solo 401(k). These will be much more nimble and efficient programs for investing in rental property. They will cost more to establish due to the legal work required to create the structure, but will cost much less per year to operate, saving you money over the long term.
Thanks for the insight. My plan is to buy rental properties as you mentioned. I have will dig in more. I will also talk with the property manager I plan to use to get their experience with self directed IRAs.