Buying your own home in the ROTH would be self dealing. Second it would not be needed since ther is a lifetime exclusion big enough to handle most gain on the ultimate sale. Third, you could not then take the deduction on your personal taxes for interest and property taxes. Finally, as I commented below, there is not the privacy because they title it FBO your name.
#1) An IRA is fairly easy to break as a creditor; there is little protection under state law for IRAs
#2) An IRA is not a substitute for a land trust, but rather in conjunction with (buy in land trust, beneficiary is IRA trustee).
#3) Buying an HOLDING real estate in an IRA is not very safe from a liability standpoint because it subjects ALL of your IRA assets to collection if suit is filed against it.