hmm, I'd say it looks OK. It sounds like you want to focus on Shadow bolt damage to max your instant casts. If this is the case I'd recomend
http://www.worldofwarcraft.com/info/classes/warlock/talents.html?0502220310230100000000000000000000000000000505000512200510531050
I say this because
bane > aftermath
faster shadowbolts and incenerates maximizes your conflag and primary spell's damage. The 5% mana isnt really importany when you have Imp lifetap.
Soul siphon > Fel Concentration
Might as well make it bigger and better than a weaker less interuptible one.
I'd also recomend Shadow and Flame and Intensity over Imp Searing pain. Once again these buff your primary shadow bolt spell. However if you love searing pain then by all means max it out. In the end its your character, play it like you want to.