I considered that, but I actually doubt that's the case. For one, if the Legendary ring was really that important, then very few classes will be viable because only a handful of classes can really take advantage of the burst so well, and that would be a sad, sad world. Further, consider that it's awkward to align your cooldowns with the ring. It may be worth it, sure, but remember that if you have to delay PC by 30 seconds then you're losing 33% of its value by simply waiting (that's the same for unglyphed Arcane power, too). At any rate, we're going to have to actually play with the Legendary ring before we can see how this plays out, and I think it's at least best to explore our options, yes?
The legendary ring really is -that- important. Losing 33% of AP/PC usage isn't too bad when you consider how the ring is
at least 56.25% multiplier for that duration. Most classes are estimating 10% or more overall gains, and it really does create rather large class imbalances. Think about BM hunters who store 15 seconds of damage from stampede with it. That's pretty hard to compare to!
On a side note, if I remember correctly, UM/OP was rather powerful with earlier PTR tuning when the Arcane trinket was a bit stronger. It doesn't hold a massive lead against the competing trinkets now. This also means that UM isn't as strong for bursting during the ring, and instead has stronger regular throughput.
