There was a post in this thread a few pages back that claimed that it's on a tier system. Effectively, if the amount of items you have falls into one ring on the dartboard Cryptic uses while blindfolded/drunk/both, you get X. If it falls into ANOTHER ring, however, you get Y. It's the dumbest way they could have possibly handled the conversion, short of simply deleting all of the items and leaving a troll face in your inventory. Why wasn't it on a per-item basis? Why do we need to be Tier 3 before we can use what we've already earned? And why, for the love of Q, are there no Omega mark rewards for Borg story missions?
I don't have a troll face handy, but will this do?