I'm a 54 WHM, and I'm torn as to whether I should be gearing toward MND(Currently +22 or 23 I think), MP(Currently around +100 and I have Dark Staff and Seer's Tunic for regen), both, or neither.
Best plan if you can afford it is get both. +MP regen is your first priority. Beyond dark staff, food, and later errant body there isn't much you can do for that. So next get all the +mp gear you can ingnoring +mnd and make this your main equipment (balance +mp later with -enimity gear you get avaiable with af and later errant). Finally, you will want to max out your +mnd as a reserve set of gear if you have the spare money for as I'll explain below.
On the occasional party where you are partied with a brd and no rdm (eg: brd, whm, blm back line) you will be the main enfeebler as whm. Many whms in this situation blow off enfeebling all together with the excuse their enfeebling is too weak which just isn't the case. :x Keep a reserve set of +mnd gear you can switch into when enfeebling and you'll be set (unless you are several lvls below the rest of the party fighting IT, then you can give up on paralyze and slow).
For me personally, I have a macro that switches in all my +mnd to boost me from +8 to +34mnd. This makes a
huge difference in my ability to enfeeble. I was able to make it all the way to 69 without having much more difficulty enfeebling than rdm's I have partied with. After you are done enfeebling just swap back in that +mp gear with another macro and you're back on track. Later you also have +enfeebling skill neck pieces available to look into buying or if you have lots of money available pick up the matching elemental staves for your enfeebles (paralze is ice, slow is earth, etc.) to drastically lower your resist rate. With the rate the prices on these staves keeps dropping this is becoming moreof an option day by day.
As for +mnd to increase the power of your cures is somewhat true, but usually your cures will cap so quickly on their own that this isn't worth messing with. By the time you make a higher lvl cure your main it is usually capped (with cure V still being uncapped for me

but its hard to fit all of that in already).