Honestly rdm and sch subs aren't that different and each have situations where I would use one over the other.

rdm:
fast cast II - 5% faster casting 2.5% slower recast than /sch
phalanx
mab II
refresh -pretty much the same as sublimation
convert -for quick mp especially useful in abyssea with high hp/mp pools
dispel- that doesn't involve addendum
sleep - again no addendum
sleep II
gravity
blind - which /sch doesn't give

/rdm I actually solo'd my wivre haipin with cataclysm and phalanx. Phalanx and a -pdt set makes whm able to pull / hold weak mobs in abyssea. Rdm seems like a better sub in abyssea because you already have highly inflated stats so slightly better boosts / barspells won't matter as much. Accession also isn't such a huge deal when you usually only have 3 other ppl in your party at max.

sch:
light arts - main bonuses for this are b+ enhancing / enfeebling. 5% slower casting 2.5% faster recast than /rdm. 10% mp cost also nice
strategems - mainly accession
sublimation - pretty close to refresh, but nice to store one up

Sch is pretty much my exclusive vw sub for better boosts / barspells and accession

blm:
sleep
sleep II
sleepga
stun
warp
warpII
dispel

All nice utility spells and I could see why someone would use /blm in abyssea, just running around doing old content or climbing vw for a quick warp after the nm is done(if you have temps).

If you subbed rdm instead of sch or vice versa I honestly wouldn't care, they aren't that different. However you should have both at your disposal.