try posting this in the proper forum next time for maximum replies. theres an 83xx forum a little farther down the page. and yes, i would say that 4.5 is worth the upgrade.
I found better battery life when moving from 4.3 to 4.5 on my curve, the phone works all day for me now, where I used to charge it over lunch to make it to the end of the work day because it was shy about an hour.