Well, you have three interrupts and nothing to slow down someones casting speed, so unless you are going for elementalists, or are quick off the mark, you may find that you miss with an interrupt more than you hit.
So, you could add arcane conundrom, maybe drop energy burn. Problem is, AC is based on illusion...hmmm.
You could also try dropping energy burn and adding backfire/shame/guilt/blackout. I don't like blackout because of the req to touch your target, but for about 65% of the time they would be locked if you stayed in touch range and cast it a every opportunity.
Shame/guilt are very conditional, but can work wonders. Not only does the spell fail, but they are drained of energy and it is givin to you (these are the only two domination based spells I can think of right now that give you energy, alibit(sp?) conditionaly)
Backfire. Many monks will either not cast till it is taken off, wait 10 seconds, or cast the hex removal themselves. I have some experience with monks, and I have noticed that, while if I have protective spirit on myself I can cast through this, it is to dangerous without that enchantment. Unless it is the last case, they will not be doing anything for a few seconds. Still, I probably would take shame/guilt over this. Then again, it is not conditional on spell type, and is usefull on 4/6 of the classes.
I like Power Block a lot. Nothing kills a monk like being unable to heal for 15-16 seconds (it is 16 at 16 dom) Of course, you need to actualy interrupt a spell, and that spell has to be a heal spell, but if you hit a monk with this, change targets! He can't do anything until it goes away (excluding sig of devotion, other divine spells, or hybrid monks*) so you might as well be harming another monk on their team. Another plus is it can not be taken off, and the only way to avoid it is to either not heal, or only cast under spell breaker/obsidian flesh (very, very few monks I have seen use the mesmer stances to avoid interruption)
*=when expecting to fight hybrid monks, or players that diversify their skill bar to a large extent, blackout is better because it locks all skills.