Seanspeed, what you say is correct, but there is no way I can know about those stuff. What I'm doing here is kind of guessing things based on what I can know and of course it is simplistic, it just can't be otherwise.
You're not guessing, though. You're saying you are *certain* of things. There's a massive difference there.
I've just realized that its very hard to tell how good somebody is going to be in F1 judging solely by their pre-F1 careers. I'm very hesitant to say anything other than, "He's got x amount of potential", ya know? Unfortunately, that potential is not always realized, and there's no sure-fire way to know which drivers will or wont acheive expectations.
Di Grassi could be good(Rosberg). He could be very good(Hamilton). Or he could be mediocre(Kovalainen). Or he could be a disaster(Piquet).
I've no problems with guesses as long as you realize that you could very well be wrong, perhaps
completely wrong. Anything more than that, and I think you're just being a little too sure-footed for your own good.