There are a few things that effect your abilities. you have stats which can determine its effectiveness like INT = Heal but there are also skill points obviously like 0 to 15 in some cases, there are also “Attributes” which inturn can be determined by your job’s “Circle”.
From what I think I’ve managed to find out, If you have lvl5 Heal for eg, but you are still Circle3 Cleric, then you have access to the Circle unlocked “Attributes” which are responsible for the majority of Heal’s maximum potential.
Assuming you have DM 10 you can then boost Heal to lvl15 and because you have the circle3 Heal attributes, you then have a maximum potential Heal on your hands, assuming you have the stats to back it up ^_~
But say you are a circle2 Cleric, you don’t have access to the circle3 Heal Attribute and so boosting the raw skill lvl of the skill will have a relatively minimum effect. (seeing as the circle unlocked Heal attributes seem to be the biggest factor in determining heal potential besides stats) Because you are only rocking a circle2 heal attribute. =P
Make sense? XD
There is a vid somewhere where you see the differenc between a max lvl Heal cast with and without max lvl DM, the increase is only around 1/5 more healing from (an assumed) approx. +60%? extra lvls via DM.
Long story short, It seems as though DM will have a minimal benefit on some skills, not all but some, namely the skills effected strongly by specific attributes so research your attributes. I’m not sure there are Monk attribute details out yet though >_<
(Not confirmed. Don’t quote meh~)