Imagine now it one is using Invocation in a heavy movement fight. One has to set idle to complete the channeling of Invocation which is quite some time to do nothing. If you must move in that time, one must start channeling all over. During movement, regardless of spec or talents, there are not many choices of dps one can do. So whether you moved out of a circle or are simply moving with or without an Invocation buff, not a whole lot of dps is getting done. For fire, of course, the DOTs continue to burn. Much of a caster's best dps is done stationary, since movement can stop most casts or channels. I know I can place two Runes of Power near each other faster than I can cast one Invocation. I can move out of something and back while both are active. Currently, the Runes also last 20 seconds longer that the effect of Invocation as well as regenerate mana as Invocation reduces mana regen.
Sure if you need to interrupt invocation it is a pain... But it has a 10 second cooldown. And most 'movement heavy fights' this raid tier seem to have very predictable movement times. And yes, RoP gives you mana regen and lasts longer, but its effect is less (15% vs 25%) and invocation gives you evocation every 10 seconds (should you so desire it) for mana regen. I am yet to come close to oom using the invocation talent as you are casting evocation every 40 seconds anyway.
I don't really see the point of your argument to be honest. It has been shown numerous times the overall effect of both is quite similar. You are trying to argue RoP is better for heavy movement fights? The extra 4.5 second cast on invocation over RoP is going to be the straw that breaks the camel's back? What about the argument that that RoP you just dropped, you can't stand in now because it is, as you say, a movement heavy fight? Recast it? Well you can recast evocation too due to the short CD.
I personally find invocation to be much better in a moderate movement fight, and incanter's ward is probably my choice for a heavy movement fight as these seem to contain some (if not a lot) of raid damage in my experience.
Could you maybe stop have us imagine situations and list a boss you think RoP clearly outclasses invocation? I don't see how a stationary circle I need to stand in can ever give me an advantage in a fight I'm running 20%+ of the time.