I kinda think you undervalued the naturalist summoner. Sure, going from SM to a trimmer SNA hurts, but if you are more eidolon-focused, the animal focus ability is actually pretty strong. At the very least it's +2 str/dex effectively permanently. But more than that, it gives a very flexible set of buffs that can be applied on the fly as a swift action. You can bump a number of skills, grant scent, evasion, increased speed or buff AoO to-hit as needed for the situation. It's like unlimited free swift-action evo-surge for certain abilities as-needed.
Even better, since the archetype actually gives the animal focus class ability, you can take the planar focus feat from the monster summoner handbook. This adds abilities like scaling bonus fire damage on melee attacks, permanent feather-fall, dealing free cold damage to attackers, natural armor bump+burrow speed, swim-speed+underwater breathing and a few more skill bumps.
Couple this with evo surge, you could have a jack-of-all trades eidolon that doesn't sacrifice combat ability. In fact, it gains some extra because you can always stick it with bull or tiger aspect for bonus stats.
I'm planning on making an aasimar summoner to take advantage of the DR/evil fcb, which is crazy awesome at lower levels. Since the archetype loses aspect, if I really want wings, I can feat into it later.
I noticed you didn't make an AoO-focused build in the guide. What about something with power Attack, combat reflexes, flying blade exotic weapon proficiency and lunge? Coupled with the large evolution (eventually), long-arm and enlarge, this could give a massive covered area. And with the flying blade bonus and the snake aspect you'd get +4 on attacks. You could also take the slam evo to cover enemies too close (maybe add push to the slam?).