lol my answer might not be what you're looking for but this from personal experience.
4. Get 3rd party silencing rings and just use regular black slider. Purple slider wobble too much and stock silencing rings don't silence that much either.
So either use silence x or deskey rings (personally I like silence x more, other people might tell you deskey rings).
But if you really really need to pick a choice out the 3, 3 is easiest probably given if mounting points are the same. However you just said one is from Leopold and one is from Realforce so chances are it will not match.
Next easiest choice is 2. dome swap. Dome swap in my opinion is much easier than popping sliders off. You just have to do it upside down and find some stuff to prop off the edges so the switches are not depressed when you're working on it.
Let me know if you have any questions.
P.S: I'm basing this from my mods with Type Heaven, Realforce 104UW, and Realforce R2. Have tried hypersphere, silence x, deskey rings #2, #3, #4, #5 and keyclack v2.