Summoners and Summon Monster

[Larkas]

Does nerfing the summoner's Summon Monster spell progression (i.e.: Summon Monster VI as a 6th level spell) affect the class's power appreciably?

(Yes, I'm aware of the Summon Monster/Gate class feature progression and the Planar Binding line.)

[grarrrg]

Does nerfing the summoner's Summon Monster spell progression (i.e.: Summon Monster VI as a 6th level spell) affect the class's power appreciably?

(Yes, I'm aware of the Summon Monster/Gate class feature progression and the Planar Binding line.)

No.
You still have the massive Eidolon Beatstick, and you still have the Summon Monster SLA's.
Effectively dropping 3 spells from the list is not going to change much.