Playing Momentum is a spec where you should know when you're going to fel rush way before hand based off timers and experience with the fight hence the disclaimer (
top simming talent if played correctly or if the fight allows you to take advantage of the talent without restrictions such as not being able to FR for long periods of time etc). You should be looking at timers of possible abilities that may require you to hold that FR in case that moment comes. Even then, you lose a lot more from Nemesis than you would with Momentum. Nemesis is a debuff on 1 target that regardless if you're in range or out of range, have a mechanic, have to swap, doesn't matter it's always ticking down vs Momentum you might have to use a couple to get out and back in and lose a little bit of momentum uptime but it's an on demand buff to YOUR CHARACTER that you can use freely vs Nemesis.
For the sake of examples lets just say the following scenario happens:
You start the fight and nemesis the boss. You are dpsing for 15 seconds, then the boss disappears, a new add spawns and it dies in 15 seconds, then you move on to the next target and it dies in 15 seconds. They are all different mob types (undead,humanoid,beast), then the boss finally spawns again. You just lost 30 seconds of Nemesis uptime = 50% downtime on your major cd. Take the same example with Momentum and you lost about 9 seconds of momentum + you were able to do increased damage to all those mob types. There's a ton of scenarios you can bounce back and fourth and most of them favor Momentum currently.
Doesn't show that for me in my current gear. The better nem spec for me would be 1311213. Maybe for your gear level, I'm not sure unless you post the sim report.
https://www.raidbots.com/simbot/repo...c8v2sgC2Mh43KW