IRAs should almost never pass through a will. IRAs pass through IRA beneficiary forms. Watch for defaults in IRA agreements if there are no beneficiary forms. If an IRA passes through a will there is no designated beneficiary and the IRA will be paid out according to the rules that apply when there is no designated beneficiary. The stretch will be lost if there is no designated beneficiary.
Naming the estate is the same as leaving the IRA to pass through the will. If the IRA does pass through the will, it becomes a probate asset subject to estate claims and probatecosts.