As far as BRD is concerned, as everyone knows BRD is pure support.
BRD/WHM gives way more support-wise than BRD/PLD, WAY WAY more. I can have up to 400+ MP on my BRD75 if I want, but frankly, even in HNM situation, I never use that much, and I'm always paired (in those situations) with a RDM anyway. If needed he can refresh me, but he barely needs to, ballad is more than I need.
Now for non-HNM situations, we're talking 70-75:
I can't think of a situation in which you're fighting mobs that:
- don't give you status effect (= you need /WHM since you need several people to -na)
or
- don't AOE (= Curaga which BRD end up doing all the time since they barely draw hate)
Actually most mobs (except for weapons in moon/sky) do both.
Considering how much I use -na and erase, there is no way I'm giving that up for +1MP/tick, considering I can already refresh myself, and that if I want +1MP/tick, there is gear that can give that to me.
For the BLM case I agree with Fire, not worth it either.
For the WHM case I still don't think it's worth it. Also, WHM subs SMN for Aerial Armor more than the 1 MP/tick I believe. Finally, I think that over an hour, Conserve MP makes you save quite a lot of MP you don't (or can't) consider in that equation.
I'm thinking /PLD for solo purpose is pretty cool though. In PT, not so much.