Heck, that's not a diversion, it's feedback!
I don't know wether to be gratified (no complaints) or horrified (no feedback to speak of) by the lack of replies it's gotten over in House Rules.
Generally, I'd say, the two Toughness effects are fine for the Alienist, even at +1hp/level. The +3hp (only) was a bit of a "non-bonus" to me, even doubled to +6hp by getting it twice ... given the inherent, potentially encounter-losing drawbacks ("Mice! BIG mice!!! AAAAAAAAAIIIIIIII!!!!!" *hysterical alienist jumps into arms of barbarian ally (completely ruining his plans for a full raging attack) as a dozen or more albino were-rats swarm the party, triggering the Alienist's insane fear of white rodents* "Please oh please oh please ... save me from the mice!!!!!" *whimper&panic*).
So, altering that to +2hp/level, while it could be powerful ... that, IMO, is only bcause they decided toughness needed to be more powerful. Trust me ... running into your phoobia, if RPed right, can be a drawback not just for you, but for anyone CLOSE to you (the poor, POOR barbarian ... heh ...).
As an aside, it always stuck in my craw that only <i>Summon Monster</i> spells get the benefits of <i>summon alien</i>. IMC, it affects any [summoned] or [called] creatures the Alienist brings about. Makes an Alienist/Druid a scary thought, doesn't it?