Piston, yeah, I've never played one but I can see why it could have gotten that reputation.
My initial build shows that the character is very powerful for a 1st level character, while the Eidolon is in play. Without the Eidolon, the character is limited to fairly weaksauce spells (useful mostly for buffing) and the Summon Monster ability which is useful, but not out of whack with what other casters of the level can do.
With the Eidolon, the character can do respectable damage, and has some pretty high defenses. Damage and AC are comparable to a well-built and equipped fighter of equal level. Effective hit points are quite high though, due to the Eidolon's contribution.
In theory this is balanced in part by the fact that the Eidolon can't be resummoned quickly if destroyed or dismissed, and precludes other summons while active. In this game, there's an additional limit of it being obviously unnatural, and inhuman, and all of the problems attendent to that (can't really walk around in a village with it summoned). That means the character can't always count on having it when it's needed.
I think it'd be interesting to see how it plays out, but I'd totally understand if you'd rather I went with something more conventional. I have concepts that make even a fairly vanilla-build ranger interesting enough for me to want to play.
