Don't hit enter after every sentence, gather related text into paragraphs. Also, your question is easy to answer by yourself using http://www.elitistjerks.com/rawr.php and setting haste to 2 in the "Effects" tab.
I have a question
From what I understand on normal conditions Fireball is better then hard casting Pyroblast
though not all fights have normal conditions, on some fights we get a huge Haste buff (usually situational and just for a short period but still) lowering our Fireball cast time to be below GCD.
My question is if my Fireball cast turns into a 0.8 sec cast, is it worth hard casting Pyroblast instead?
are there other situation where hard casting Pyroblast is preferable (apart from use of ignite)