Well, at higher lvls, youl will have a mana problem depending on where you hunt. If I hunt in varka, I can go about 2 hours before both me and the SE are out of mana, and I have passive clarity as an augment. But in IoP, I could go on w/ no mp breaks at all.
As for pvp, I enjoy my sps. Most will say they arent the best but if you know how to play them you can kill almost any class. We get 2 vortex's, and ice vortex crusher at 79. Aura flash (all mages do i think), it's a close range aoe that has a chance to remove the persons target (works for pve and pvp). Also we get blizzard, which hits hard as hell and if lands it gives your target -50% run speed.
But if your looking for a hard hitter and something to help your main w/ sub to main skills, sps is not a good choice. I would go glady,tyrant or destory...for boost cp or chance haste.
Or the Silver Ranger is a pretty good choice as well, you can get a pretty good ++crit passive. An archers can take out most classes at higher lvls as well.
I like spellsingers, yeh... lemme explain exactly what I like about them.
Undeads can be found anywhere in the game, so Solar Flare becomes a handy spell, as it deals insane sacred damage.
The curses fear and weakness, along with sleep, help me and my party stay alive when for some reason there's way too many strong monsters willing to chop our heads off.
My WIT advantage allows me to boost my INT through items, as well as my MEN advantage provides me with magic critical hits and low spell cancelling rate.