Any judge of probate, who is not a full-time judge under the provisions of N.H. Rev. Stat. § 547:2-a, who retires upon becoming 65 years old after having served in such capacity for at least 20 years, shall receive thereafter and until his death a salary equal to
3/4 of the sum of $19,102 plus an adjustment proportional to any general pay increase granted to judicial branch employees. Such payments shall be a charge against the biennial appropriations for the probate court, and shall be included by the administrative office of the courts in its request for appropriations. Retirement payments as provided in this section shall be in lieu of any rights or benefits under the New Hampshire retirement system to which such judge would otherwise be entitled. Any judge of probate who is a member of the state employees’ retirement system or the New Hampshire retirement system may terminate his membership therein and upon termination any accumulated contributions shall be paid over to him on written request. No judge of probate whose membership is not so terminated shall be eligible for payments under this section.