Well if you wanna level as Balance and feel like mana is a problem just do a hybrid spec ^^
http://talent.mmo-champion.com/?drui...33013005300000
You loose alot of dmg, but for solo grinding mana isn't an issue. I've been normal and this balance spec, with my gear (kara/za/badges), Newly dinged 70, i've got about 300 mp5 unbuffed - I've got resto gear only mind, since i didn't think balance was fun at first so i didn't bother with the gear, still i can get on top DPS everywhere with this spec - You just have to play the rigth way for your spec - Normaly i offheal/dps and still manage to get high dmg.
The best thing is if you don't need to heal at all (in raids where healers do their jobb) like when i did Supremus (BT boss 2) with a pug, i didn't need to heal at all, i didn't go below 90% mana and i spamed dps the whole figth.
Tho i prolly should ad that i'm gonna go for a normal Balance spec in wotlk, gonna instance grind to lvl 80 (I don't wanna re-live the nigthmare scene that occured when BC came)
Well that's just my option.