er, the circlet part i don't really agree... unless you're using them later to get nulls.
175 is not that cheap early on, and 5 circlets would get you a mask of death, nearly a point booster, w/e... i'd rather wait a little bit and go straight for my item...
About lion - unless you're in a clan match, when you trust in your mates, you should go aghanim... IMO. Going straight for guinsoo gives you nothing but intelligence, leaving you totally vulnerable to a simple 2v1, for example. Lion got very low hp...
with the +400 life and + 450 mana given by soul booster, you can spam your spells, gain mana regeneration, life regen, and have the extra hit points edge. AND not saying that FoD will still be a decent spell @ high levels if you have aggy scep..
on the other hand, guinsoo works VERY well in clan matches, where you can disable 3 guys at the same time, not to say that a well placed impale can stun more than it.