The question of whether to pursue a Multi-Engine Instructor (MEI) rating on top of CFI and CFII certificates is a perennial one in the flight training community, and it sits at an important junction point for pilots building time toward the airlines, corporate flying, or Part 135 operations. The original poster, having just earned a multi-engine rating and working through CFI and CFII, is weighing the additional cost of MEI training against its career value. This is not a trivial decision: MEI training typically requires renting a twin-engine trainer like the Piper Seminole or Beechcraft Duchess at rates that can run $300-500+ per hour wet, on top of instructor fees, potentially adding several thousand dollars to an already expensive certification path that includes private, instrument, commercial, CFI, and CFII.
For working pilots and flight instructors, the MEI rating carries outsized importance relative to its cost because it directly determines earning potential and hireability at flight schools. Multi-engine instruction commands a premium hourly rate compared to single-engine primary instruction, and MEIs are in persistent demand because far fewer CFIs pursue the multi-engine add-on than pursue single-engine instructor ratings. More critically, MEI time and multi-engine PIC hours are exactly what regional airlines, fractional operators, and Part 135 turboprop and light-jet operations screen for when evaluating low-time pilots. A CFI without an MEI is effectively locked out of building multi-engine time efficiently unless they can find another path (right-seat SIC time, for example), which is far harder to come by without an established network. In an environment where airlines and business aviation operators still value multi-engine PIC hours heavily in hiring minimums—even as the pilot shortage has loosened some numeric requirements—having logged, instructional-quality multi-engine time on a resume is a meaningful differentiator.
Beyond the immediate financial calculus, the MEI decision reflects a broader trend in flight training economics: the traditional CFI-to-regional-airline pipeline increasingly rewards those who can accelerate through multi-engine time efficiently, since most flow programs, cadet programs, and even Part 135 operators now look favorably on candidates who instructed in complex, high-performance, and multi-engine aircraft rather than exclusively in Cessna 172s or similar trainers. Flight schools that offer Seminole or Duchess fleets also tend to have more relationships with regional partners, creating a virtuous cycle for instructors who hold the MEI and can teach in those aircraft. For an instructor who has already expressed enjoyment flying the Seminole, as this poster has, the MEI also opens the door to teaching commercial multi-engine add-ons and initial multi-engine ratings to other career-track students, which are typically billed at instructor rates well above primary single-engine dual instruction.
The tradeoff is real, however: MEI training is genuinely expensive on a per-hour basis given twin-engine fuel burn, maintenance costs, and insurance, and for CFIs who plan to build time primarily in single-engine aircraft (towards a bush flying, aerial application, or single-engine charter career, for instance) the return on investment is far less clear. But for anyone targeting the traditional 121 airline path, a fractional/corporate flight department, or a Part 135 twin-engine or light-jet operation, the consensus among working instructors is that the MEI pays for itself quickly, both through higher billing rates as an instructor and through its function as a career accelerant. This is a case where a several-thousand-dollar upfront investment tends to compound significantly in flight time, hiring competitiveness, and instructional income over the following one to two years of building experience.