Topic: Date & Time or DateTime?

I've initialized by database with separate date & time columns, but I'm beginning to learn that Ruby/Rails handling of Time is such that it effectively treats it as a time with a date prepended, the the controller logic is unnecessarily convoluted, and comparing events across two different days potentially complicated (may not be an issue in my particular use case where events are less likely to happen close to midnight, but still...)

Am I better of just Using a single DateTime column, or is there any benefit to keeping them separate?