I appreciate the leads. For ethical, religious (husband's, not mine) and omg, please not twins reasons, I'm leaning toward one. But since I've never done a DE cycle or been pregnant otherwise, and funds are limited, part of me toys with transferring two.
(Then again, if you transfer two to "save money" and end up with twins, you aren't really saving any money at all in the long run. Quite the opposite.).