that is a tough decision. that +2 EAC in PVP is only taking up 1 space and gives good spike DMG. EAC also is doing 100% of the original attacks DMG, but you only have a 50% chance for the EAC.
Multi Attack +2 in PVP takes up 2 spaces, unless you have it on an Eternal Item. it gives you the extra attacks at the same time as your original attack, but the DMG is 50% of the original.
to be honest, if you are going to give up a space for MA, may as well keep the +4 EAC and just have 1 MA. or just do test to see if either way makes a better difference or not. that is 1 extra attack all the time with 50% DMG, with a chance for 2 extra attacks doing 100% DMG each.