We keep our Rogue on the boss full time. Doesn't need to soak pools either. Just DPS.
Let's not exaggerate I'm a Holy Paladin and I soak with Hand of Purity and Divine Protection, and can also remove the DoT with Divine Shield. Don't think a rogue can beat that. Especially not because soaking near the boss isn't really all that useful and you would lose DPS to soak pools away from the boss.
First of all, you dont have melee soak ranged pools. Melee soak melee pools, and these are the more important to clear out as well due to there being less space.
Secondly, paladins aren't nearly as good. The pool, on normal mode, does 3 ticks of 100k damage, at which point it disappears. You are left with a dot that ticks 3 times, 5 seconds apart, 50k each. This dot is basically meaningless; the dangerous damage is the 300k in 3 seconds.
A rogue can reduce that by 65%. A paladin can reduce it by 40% with divine protection. Hand of purity reduces the dot damage substantially, and 10% of the pool damage. This makes it roughly equal, although part of the paladin's benefit isn't as important, as 150k over 15 seconds is basically nothing.
A rogue can immune the stacking debuff once per minute. A paladin can remove it once every 5 minutes.
And here's the big one. This is a no-brainer. Rogues can spam feint. You can take one pool after another after another after another. Paladins can take 1 per minute, and will stack the debuff for 5 times as long before being able to clear it.
This is not even close. Rogues are vastly superior.
Side note, if you as a holy paladin are designated to soak lots of ranged pools, you should probably drop purity for unbreakable spirit. You will get ~50% more divine protections, and an extra bubble. If your tanks absolutely need purity to survive, then i guess do what you have to do. They should be able to live without it. Remember that when soaking pools, the dangerous damage is not a dot, only the wimpy 150k over 15 seconds.
I've participated in the nest strike team, and stayed on the main platform in our 25m. Both roles can be filled effectively by a rogue.
If you're doing nests, I suggest marked for death...the adds die quickly, multidot the adds, fok after envenom. Used mark around 30-40% on an add, envenom then dispatch. Tried to redirect if possible...but you've got marked for death. Save smokebomb for quills if they hit you on one of the platforms. Don't use your mark on the boss itself, don't want to wait the full minute cd for it to be up again for nests spawning. Abandon nests and lust on the boss with everybody on the main platform just below 30%.
If you're on the main platform, use the feint talent for 30% dmg reduction, and soak melee pools. We usually take 3-4...but if you start taking heavy dmg, use cloak to drop your stacks and start soaking melee pools again. Use anticipation if you're going to be sitting on the main platform. Keep in mind soaking pools gives you a dmg buff as well...so be sure to eat those pools. Be aware of downdraft and quills. Don't EVER soak a pool during quills or your healer will hate you.
A couple helpful macros when using MFD in PVE
For MfD + Envenom:
/castsequence [nomod] reset=20 Marked for Death, Envenom
For Envenom, MfD and a new Envenom:
/castsequence [nomod] reset=6 Envenom, Marked for Death, Envenom
First here is a top 20 rank for this fight as assasin rogue (worldoflogs.com/reports/rt-vo3htztxyzbjmuyn/dashboard/?s=2319&e=2855)
My role on heroic is to do nest 2 and nest 8 (where you land upon entering the bosses room). Start the fight pop all your cds they will be back in time, when nest 2 is up save 5 cps for an instant CT upon landing. Rupture up a few adds and aoe. Grab your feather and wait for the boss to caw, after the caw use feather to get your first nutriment and dps boss. You then have 2 more feathers.. one with be with all your cds popped (i believe i skipped the second feeding) and the other will not. When you go down for the 8th platform you only get 2 usable feathers in my assignment since waiting for a proper time will keep you inactive far too long.
Time your last feather with all cd's and lust + potion (praying on trinket procs).
Other logs i have seen show rogues getting more then 2 feathers (there was a time where i could grab a feather in the middle but i figured i would lose 10-20 seconds to gain 1 more nutriment buff and didnt want to risk wiping to try it.