Data Validator or Modified Java Script value

Hi All,

I have a file which contains at least 30 date fields covering almost all date conversion masks as follows:
DD-MMM-YY
MM/DD/YYYY
MM/DD/YYYYHH24MISS
MM/DD/YYYYHH24MISS OR MM/DD/YYYY (Field can be in any of the mentioned format)
MM-DD-YYYY
YYYYMMDD
YYYY-MM-DD

I have to validate the date fields. I understand that it can be done as:
1. Use Data validator specifying different Conversion Mask
2.Use Modified Java Script Value with str2date(INPUT_DATE_FIELD,DATE_FORMAT)


Performance wise which step would be better to use for data validation ? Also if any better way to validate dates?

Sorry if the question is too silly, I am not from Java background and very new to Pentaho.

Regards,
Bishnu