I really don't think this is the issue. I don't mean to sound like I have a massive ego but I believe I can play it to near perfection; and the odd single cast break won't account for many thousands of DPS in a fightA couple of things to consider that gives SN an advantage over UM on actual boss fights.
1. On actual fights you actually end up interrupting quite a lot of spell casts, either by (accidental) movement or because you realize it was the wrong choice to cast AB or one of the many other reasons you could think off. The total UM damage you can do is limited by the amount of AB casts you can get off in a fight (which is reduced by interrupts) and your total SN damage is mostly limited by it's cooldown. Especially since it has 2 charges you're almost always gonna get the maximum amount of damage out of your SN.
[quote[2. SN is instant cast and can be used while moving.[/quote]
This is kinda irrelevant. Even on low movement fights like Reaver and Fel lord, or combat dummies, I had noticed the damage discrepancy was much larger than it should apparently be.
Nope. The only time supernova is ever delayed is the first one, which gets used soonafter on the crystal. My supernova never waits on 2 charges, and 2 charges get blown into every crystal. If anything, I'm certain that my play regarding Supernova is more optimal than Robomage; with using Supernova during trinket procs/high Incanters stacks, as well as keeping other factors like mana/number of arcane missiles in mind.3. (speculation) in real life situations it's quite likely that you delay your SN's for longer then robomage would because your play probably isn't as optimized. Hanging on to some charges of SN gives you the ability to use them to fish for more missiles procs when you get PoF procs. I've been using my SN's for this purpose quite a lot and I strongly believe it's a big DPS increase. (to bank 1 charge in order to fish more AM during PoF) maybe someone smarter then me could sim this?
I'm thinking UM is just so susceptible to RNG. Getting no procs on PC, and less Arcane missiles (due to no double supernova hits and mana recovery), burn phases can be absurdly short lasting