[andrewf]

What are they trying to improve? Stability? Time from change request to change appearing in production? Developer velocity over time? Sometimes you'll hear things like "this will cost an extra $1000/month but make hiring and retention easier"

Operationally: You need a few more/different specifics to avoid talking in generalities. How many requests per second? What's the floor? What's the peak? How bad a sudden surge ("thundering herd") do you ever see? What's the heaviest request / worst case response time?

Then you can start comparing the two solutions under various scenarios. How much will our average RPS cost us? Will the service deal well under very low or very high load? What happens when your worst-case thundering herd hits? Does your heaviest request fit comfortably within limits?