How good each one is will vary with your other gear, your buffs, and what you are fighting. Generally speaking, the 10 acc/3 DW should win for NIN.
You shouldn't need a whole lot of math to see the difference. 3% DW, with 75 NIN and Suppa earring, takes you from 35 to 38% delay reduction. Say you have a combined delay of 417 (Senj/Perdu). Without Mirke, your delay is 271, with Mirke its 259. Your DPS on your weapons (damage and delay combined with DW factored in) is going from about 15.5 to 16.2, or a 4.5% net increase in weapon DPS. Say you have 350 attack, a +10 attack increase is only going to bump your damage on normal attack up by about 2.9% or so. The more total attack you have, the less of a % increase you will gain from the +10 attack, but the DW enhancement will still provide the same % increase in DPS. In other words, the better geared and more heavily buffed you are, the less that 10 attack is going to matter, but the DW will still provide the same extra added speed.
Another thing to consider is what you use each job for. If you will only be using NIN to tank big things as NIN/DRK, you likely won't find Mirke to be all that useful. If you plan to use your MNK for damage and your NIN for tanking, maybe consider the MNK Mirke.
____________________________Jacs of Leviathan
SAM, MNK, THF, NIN, SCH, DRK, BLU 90
Woodworking 100+3, Synergy 57