/sch will still be better. Stratagems.
RDM Convert vs SCH Penury -
If you penury 5 spells, we'll use Cure 5 for this, each cast you'll save ~60 MP, so that's 300 MP, plus the -10% mp cost on each spell so it'll even out over the 10 minute recast of convert.
Then you have Refresh vs Sublimation. Sublimation is only 2mp/tick but doesn't cost anything to cast. Refresh is 3mp/tick, but costs 40mp to cast, so for 40 ticks, you'll be getting the same as sublimation... So you have 10 extra mp from Refresh than you'd get from Sublimation... Once again, the -10% mp/spellcasting time trump that.
And fastcast, for /rdm it's -15% on all spells, /sch is -10% on the arts you have up, but if you need, you can pop celerity and -50%... This is the only place RDM is overall better... But not enough to sway the subjob.
And... SCH still gets accession, which personally I find best used on stoneskin or Regen 3. My regen 3 does 25/tick for 20 ticks, so that would be 500hp cured on everyone in the party... for 128 mp... That in and of it's self is nice, considering curaga 2 is 120, and even w/ a max potency set, you might be able to break 300/person.
Just my two cents.