In the case of a subdivision or site plan for a Planned Development of 50 acres or more, conventional subdivision or site plan for 150 acres or more, or site plan for development of a nonresidential floor area of 200,000 square feet or more, the Municipal Agency may grant the rights referred to in paragraph d1 of this subsection for such period of time, longer than two years, as shall be determined by the Municipal Agency to be reasonable, taking into consideration (1) the number of dwelling units and nonresidential floor area permissible under final approval, (2) economic conditions, and (3) the comprehensiveness of the development. The developer may apply for and the Municipal Agency may thereafter grant, an extension of final approval for such additional period of time as shall be determined by the Municipal Agency to be reasonable, taking into consideration (1) the number of dwelling units and nonresidential floor area permissible under final approval, (2) the number of dwelling units (3) economic conditions, and (4) the comprehensiveness of the development.