I'll change the healing magic to 430 and retest a larger range for you tomorrow.
Unfortunately this doesn't seem to work for me, upon changing primary job level, the dialogue with the GM moogle closes. Skills are auto capped whenever you use the change main job level function.
Actually, that's pretty much what I've been doing to get the lower bounds values, the trouble is that it becomes a very complicated juggling game of stats. Adjusting merits, trying to find magian trial staves with appropriate stats, and hunting through claim slips for gear.
The main trouble I've been having is that I'm attempting to vary one stat, whilst maintaining the other 2 so we have less variables to worry about. Although, that said, if we became 100% sure of the formula, in theory we could just work with cure-power and graph any combination of job/level/stats/skill.
I'm on nightshift tonight, so I'm afraid I won't have time to do it today... however tomorrow I'll make a much larger sample size of MND and VIT scaling, which'll hopefully help confirm Motentens formula. I'll then change my main spreadsheet to work with cure-power rather than with skill, and then work on getting the lower bounds.
I'm actually surprised that the change to the formula isn't being more discussed... it has a huge knock-on effect across the other jobs.