How much spell penetration needed with new contents?

[Fanaval]

Hello!

I have a wizard in TR and I have 3 PL wiz and 2 PL Fvs.

For the future build of my wiz i need to know how much to invest in spell penetration considering that I have a bonus of +8 (or if i tr again +9) on Spell penetration from Past lives.

Expecially I'm interested to know if the new contents of Epic Gianthold and Shadowfell require a high SP. What is the highest spell resistence of monsters in EE in those packs?

I want to calculate if for example feats like Epic spell penetration that were absolutly necessary in Motu are now worthy. Of course an epic feat slot to use for a more useful purpose like the new spell Ruin or epic spell focus necro is good.

Thank you very much.

Edit: Another question: Is a favored soul life worth now or is better to do other lives like bard for +1 enhancement or something else?