He doesn't throw as hard, and scouts think his stuff is simply a tier below, especially his fastball. So yes, that would constitute decidedly inferior, and yes, i will take scout's opinions over yours.
By the way, here's an excerpt from Gabe Kapler (yes, that Gabe Kapler) from foxsports regarding Tanaka immediately counteracting part of your point:
And here, he quickly counteracts the second:
Basically no, Tanaka is not in the same level as Darvish. That's not necessarily a knock on Tanaka, since Darvish is a freak, but it's ridiculous that he'll probably be commanding more money overall.
Btw, here's the linky to the Kapler article: http://msn.foxsports.com/mlb/story/kapler-expect-tanaka-to-land-big-bucks-in-unprecedented-bidding-war-122613