i'm a really melee kind of guy but after the recent changes to the game i felt compelled enough to roll an arcane.

i went for a wf necro/conj archmage (lvl12 atm). i went for conj secondary instead of enchant in order to have a cheap and effective CC option i can use also when OOM. the planned feats are:

2x S.F Necro, 2x Spell Pen, Though, Mental Though, Extend

Bonus Wiz feats:
S.F Conj , Heighten, Maximize, Empower, Quicken

i was considering adding insightful reflexes to the mix to boost my survivability but the issue is what to drop for it.
i would drop thoughness but i want to keep open the option to easily respec to PM.
so i was considering extend, as it is useful only for an handful of spells (haste, rage, displacement and fire shield maybe).
are there serious downsides? any other alternatives?