If Summoners gain Summon Monster "X" as a spell-like ability, and this ability gets stronger the higher level the summoner is, does Dark Magic Affinity mean that a level 2 Summoner can now cast Summon Monster II instead of Summon Monster I?
Logic Chain:
Spell-like ability = casting the spell, Summon Monster has "Evil" descriptor if you summon Fiendish creatures.
Dark Magic Affinity reads:
Whenever you cast a spell with the [evil] descriptor, you act as if you were one level higher for the purpose of determining that spell’s effects.