I'm guessing the pessimism is like you say more a self defense mechanism. But oddly enough, there are times or some matches, where you kind of wake up feeling a certain way in a good/bad way. What are you feeling this particular time? The reason I ask is, because while everybody has Barca at overwhelming odds on favourites, this final has us in so many ways as a unknown quantity. We honestly don't know how strong or how weak we will be at the true summit of Europe. My heart obviously goes with Juve for tomorrow, somewhere, I feel destiny and serendipity, I guess I take heart in some coincidences like Berlin, perhaps the law of averages for Barca always winning finals and us always losing em. But again, there is a lot of measure in emotion because I don't want to get carried away with soft statistical coincidences.
One thing though, that I feel a lot of experts and players have missed out on us the psychological aspect of the game where I feel Juve are hungrier, and more of a team in that sense, where they will sacrifice for each other. Barca have been in this position before, and this time, while they are stronger than ever, I also think/feel they're more about individuals than a collective.
I don't know if I'm pessimistic about tomorrow, but I am pragmatic. If I was to call this, as per the way I read us and the Barca way of doing things, I can see it as a stubborn slugfest, where Juve will start controlling things the longer they go on. Also, like you said if we get off to a good start, this team has the maturity and intelligence to build on it, rather than hand the initiative back to Barca.
All this said, there's just too much emotion at stake and I don't know how to deal with it. Whether I should stick to my superstitions - sitting on one particular sofa, in one particular set of clothes, with the lighting a certain way etc., or share it by calling some friends over to help absorb the palpable energy.
Anyway, all this said, you still didn't answer which way you see it go? Be it head or heart.