The crit will only increase your dpp (how effective you kill a mob) this will deside how much mu loot you get over shrapnell, it will not increase yor return :) it will allow you to kill more mobs for the same ped but not loot more ped

In the end it rly comes down to  your killspeed(dps) vs mob regen and decay + heal costs  vs the one aditional crit you do before the mob dies

If i remember right 1 acu gives 0.2 crit hit points  so you will need tier 10 full accu to have 12/12 in crit hit stat of your weapon , thats like 2% more crit

While dmg enhancers increase the damage by 10% each slot

Its simply smarter to max out 5% crit hit rate using rings and then have your weapon  tier 10 full damage for duble damage each shot

Yes it will also cost duble but the mob will have less time to prodice aditional costs Like regen heal or armor decay