Are cryovials really better than regular tubes for cryopreservation?
I do not have data to back this up, but can say that from experience, cryo vials are a much better solution for storing your valuable cells. First, their plastic is thicker, meaning they’re more sturdy and can handle a deep freeze much better. The killer feature is the screw caps, which means that they will never pop open accidentally due to mishandling or temperature changes (which has happened me with samples in microcentrifuge tubes). These screw caps also allow much more efficient storage in expensive cold conditions (liquid nitrogen will be best for cells long term) and easier retrieval from boxes that are freezing cold. 

Microcentrifuge tunes may suffice but cryo vials exist for a reason.