Switching targets hurts when using RoW. It doesn't matter if you're using haste or mastery. It hurts, period. You take a 10-15% hit to your damage every time you switch, so if you do it often, that's how much DPS you'll lose over the course of the fight. I've been getting questions like this for months, and I feel like it's a loaded question. Like people are searching for a specific answer. What answer are you hoping to hear? RoW sucks for switching targets, there's no magic gear combination that's going to make it suck less.
Haste is more forgiving than mastery. It's a better stat when glass chewing, and it's a better stat if your skill-level is low or average.
Mastery has a higher skill cap. It's more punishing if you handle it poorly, or you just aren't good at sniping Deaths and maintaining RoW stacks. However, it's very good with short fights where Heroism and execute make up a large percentage of the fight.
If you're bad at managing stacks, or you can't get the Haste rotation working, I really don't think switching to mastery is going to help you, because both methods take a great amount of effort and skill to use. There's no magic combination of stats or play style that's going to make this trinket any less of a pain in the butt. Excepting the aforementioned haste build, which I really do feel is the best build for "most players" because it requires the least awareness and attention.