Swap bombardiers out for meticulous bolts, swap your rings for Focus and Restraint (your CoE is a 38.75% damage increase, even at 200% it would only be 50% and the wailing host is useless). Swap marauder set for unhallowed essence and use lightning rune on elemental arrow and fire a hated spender only to proc Restraint, elemental arrow - lightning ball this will far outdps what marauders could achieve, and unhallowed's 1215% damage increase beats marauders 500%. Your bolts will hit enemies 2-3 times this way for 600m+ each, if you keep sentry - polar station in your build, you can increase that to 3-4 times against enemies inside your polar stations as well as proccing bane of the trapped easily without maelstrom. You wouldn't need Iceblink this way either.
If you want to keep Marauders and your Kridershot, you're going to have to swap bombardiers for meticulous as the damage is too much to pass up. If you want to be a cluster shot build though, then you have to swap your Krider out for a crossbow. Bows are bad in general as they are resource inefficient, the only reason to use a Krider is for meticulous bolts & lightning ball.
If you do the smart thing and swap to focus and restraint/unhallowed essence/meticulous bolts, then you want attack speed on EVERYTHING except jewelry. You want:
UE Shoulders - Dex, Vit, Resist All, CDR,
UE Helmet - Dex, Elemental Arrow %, Crit, Socket - Diamond
UE Gloves - Dex, Crit, Crit Damage, Attack Speed
UE Chest - Dex, Vit, Life %, Reduced Damage From Ranged Attacks, 12 Max Discipline
UE Legs - Dex, Vit, Life Regen
UE Boots - Dex, Vit, Resist All, Elemental Arrow %
Lacuni Prowlers - Lightning Damage, Dex, Attack Speed, Crit, then roll Movement Speed into Vitality. Lacuni's are extremely rare and hard to have them naturally roll like that though, so a good set of Steady Strikers will work. On them you want Lightning, Dex, Attack speed and Crit.
Kridershot - roll 10% RCR to 7% attack speed and you're golden, your Kridershot is a monster.
Meticulous Bolts - Dex, Attack Speed, Crit Chance, CDR, Elemental Arrow %, 12 Max Discipline
Build - Elemental Arrow - Lightning Ball, Multishot - Fire at Will, Preparation - Invigoration, Vault - Tumble, Marked for Death - Grim Reaper, Animal Companion - Wolf Companion
Enjoy facerolling 55+!
I honestly think you should go the blue balls build as you have the hardest and most important component - the Kridershot. The only build that can stand up to UE bluebawlz is Natalya's, you're hurting yourself at the minute by using Marauders, at least until somebody figures out a completely new spec other than the one from last season.
I don't think 15% additive damage beats 8% multiplicative damage tbh! Though you're right, you can roll both on a quiver at the expense of vit or attack speed, but honestly that's next to impossible, getting 10 crit and 12 discipline is hard enough.
Also 15% multishot equals 1 point of discipline, that's like 1.3% extra DPS as somebody showed in this thread. 8% RCR on a hatred spender build is 8+ % extra DPS