In FFXI endgame I knew some people who used DPS spreadsheets to calculate their average DPS for a particular boss/monster. You pretty much had columns to enter your gear/stats and that would be matched using a proxy RNG and the approx lvl/stats of the boss you picked or something. After playing with different gear sets you'd know what would be the best investment in terms of stats (e.g. needing higher accuracy for coil content etc)

Here's what I'm talking about:
https://docs.google.com/folderview?i...&usp=drive_web