I found upgrades on CO Micronesia to be quite easy to come by. Kwaj girl (OP Gold) and I (OP Plat) lived on Kwajalein for four years and we received free upgrades almost without fail on the KWA/HNL and HNL/KWA flights. In the past few months CO Micronesia was included in the automatic upgrade system (before that, you had to call the elite line and request your upgrade for CO Mic flights) and I had 100% luck in getting automatic upgrades.