Cata DoTs

Cataclysm will not be allowing (or demanding of) you to front-load the crazy empowered crit SrpS for the Chimera to refresh for the entire fight.  That sounds like good news to me.  I don't like flipping into my T9x, T10x2 set in LK and wont want to do something similar in Cata.

HoT and DoT refresh
Dots and hots adjust on the fly now when they're refreshed. There is less reason to try and get everything lined up perfectly for big numbers before you cast the spell. You'll be able to game it a little bit for the initial spell duration, but it won't refresh infinitely with the big numbers.

We have to rebalance the entire game anyway given the magnitude of the Cataclysm changes, so don't worry about being penalized for any old mechanics that may no longer be relevant. (Source)