I don't think I'm entirely sure what you mean, but my best guess is "no."
What makes something tier 1 is the ability to do things that will break the game master's vision for her world (teleporting the Ring to Mt. Doom, thereby invalidating half of book 1, all of book 2, and two thirds of book three, for example). This means you need access to magic, and lots of it, to be tier 1 (barring a major thematic redesign).
If you simply gave summoners access to the wizard list, I don't think it would make them tier 1, because they're still spontaneous casters with a limited number of spells known (basically, sorcerers), and because they're 6th level casters (basically, sorcerers light). Of course, this would also "change his spellcasting."
If you gave summoners wider access to summoned monsters than the standard SM list, that might do it. If you allow, for example, summoners to summon any encounter of CR equal to their level -- for example, a 5th level summoner summoning 16 orcs or a 18th level summoner summoning a cairn linnorm, that would probably do it. If nothing else, there's probably something summonable that would give them access to wish, and that would definitely do it. This isn't technically changing spellcasting because the summoning is a spell-like ability, but it still feels like it's something you wouldn't like.
You could similarly add potential evolutions to the eidolon that would turn IT into a tier 1 character, but again we'd be talking about spell-like evolutions.
What makes something tier 1 is the ability to do things that will break the game master's vision for her world (teleporting the Ring to Mt. Doom, thereby invalidating half of book 1, all of book 2, and two thirds of book three, for example).
No. A tier 2-3 character could teleport to Mount Doom... but would then lack the willpower to throw the ring into the flames. A Tier 2 character would have Nine Lives and Mind Blank active to have a good chance to save against the Ring's mind affecting effect. A tier 1 character would prepare Mage's Disjunction a few times and destroy the ring without ever leaving Hobbiton... and than go on reclaim Moria because f%!* it, it's only 10 AM you gotta do something with the rest of the day.
If you simply gave summoners access to the wizard list, I don't think it would make them tier 1, because they're still spontaneous casters with a limited number of spells known (basically, sorcerers), and because they're 6th level casters (basically, sorcerers light).
I'd say that would nerf the summoner. The early entrances and level discounts are what make the summoner's spellcasting so crazy.
There is no hard line, but the difference between tier 1 and 2 is basically pure flexibility. Summoner is a Spontanous Caster, so in order to opush him to Tier 1 you would need to work that angle. Something like Spell Kenning/Knowledge Pool or Razmiran Priest's ability would go a long way, as would more SM options for more outsourced spellcasting.
Take away the eidolon and allow the summoning SLA to be used to cast any conjugation wizard spell of an equal level summon monster. And that should achieve tier 1.
If you gave summoners wider access to summoned monsters than the standard SM list, that might do it. If you allow, for example, summoners to summon any encounter of CR equal to their level -- for example, a 5th level summoner summoning 16 orcs or a 18th level summoner summoning a cairn linnorm, that would probably do it. If nothing else, there's probably something summonable that would give them access to wish, and that would definitely do it. This isn't technically changing spellcasting because the summoning is a spell-like ability, but it still feels like it's something you wouldn't like.
"Creatures summoned using this spell cannot use spells or spell-like abilities that duplicate spells with expensive material components (such as wish)." Taken from the summon monster description, so they'd never get that wish.
"Creatures summoned using this spell cannot use spells or spell-like abilities that duplicate spells with expensive material components (such as wish)." Taken from the summon monster description, so they'd never get that wish.
Make an exception to that rule that only applies to the Summoner's Summon Monster SLA, and you have your Tier 1 Summoner. Well, Tier 0 at level 11 if you pick up Summon Evil Monster and get access to over 20 free Wishes per day.
"Creatures summoned using this spell cannot use spells or spell-like abilities that duplicate spells with expensive material components (such as wish)." Taken from the summon monster description, so they'd never get that wish.Make an exception to that rule that only applies to the Summoner's Summon Monster SLA, and you have your Tier 1 Summoner. Well, Tier 0 at level 11 if you pick up Summon Evil Monster and get access to over 20 free Wishes per day.
Or simply summon something with miracle instead. No material component (in general).
Are there even summonable creatures with Miracle?
Are there even summonable creatures with Miracle?
Not on the standard list, but a few in the more general bestiary.