1) Will you maintain Mongrel forever? It's not your track record that's the question, but the one of all future maintainers of Mongrel that will have to deal with the added complexity this change creates.
2) The experience from 1992 still seems current. Adding complexity to any software project adds cost to maintain it in the future. My experience in 1992 showed how added complexity for a marginal performance gain did not pay off then and still won't pay off today (unless you are programming a computer so expensive even a marginal increase in performance means lots of money).
3) It's your project and you may do with it whatever pleases you. What I wrote was intended as friendly advice from someone who is in this business for a long time. You are, of course, free not to accept the advice.
4) I encourage you to try new things and I am usually the first to propose workload-adaptable solutions. I, however, had my share of extremely clever optimizations that bit me back later when things as subtle as processor caches changed and it's not very funny (albeit it is fun to dig deep in the system to find out why X runs 33% slower on the 50% faster box). Nowadays, I consider every program line not written a line gained.
