In raid im afraid not mate, since even during our burst phase where all of our casts are instant you will still be stationary due to Rune of Power being the best talent, after that you will be hardcasting fireball alot of the time. Forced movement is certainly less of an issue for fire mages however due to the ice floes talent, instant pyros, phoenix flames, fire blast and when you have run out of those scorch is castable while moving, so out of all the casters for raids i would say fire mages are top tier for mobility/damage, but i'm afraid your highest possible sustained damage output means you will be standing still the majority of the time.
PvP is very different however, with the right talents (flare up) in arena you do not need to cast to output your burst damage since the combo is all instants, even when trained you can only be shut down by stuns or a silence, which makes you very strong in comps that center around massive burst during DR cycles then playing defensive until the next cycle, such as RMP.
The only spell you will be casting constantly is polymorph which again you can protect with the right talents, shimmer and prismatic cloak for example. When you are free to cast you just spam fireballs into your target since you will be most likely running the firestarter talent, which reduces combustions cooldown by 10s per fireball cast, allowing you to burst again sooner than it takes for defensive cooldowns and trinkets to reset so even squeezing out 4-5 fireballs is super strong.
And then there is dragons breath, one of the few instant aoe cc's left in the game, it is such an amazing ability on a short cooldown that provides so many different setups or sick for peeling, interrupting or making sure you can land that clutch poly, this ability is the icing on the cake for fires toolkit.
So after all that, i guess you need to ask yourself if you can put up with the semi-static playstyle required for raids then you wont regret rolling as fire, since they are going to be top tier in pvp as well.
EDIT: Or yeah play Hunter