No, it wouldn't conflict with my plugins, but it would conflict with the Links SQL core code (that's what Alex also said, if you carefully read his post above).

For example, the new links feature will be completely broken. Have a look at the code in Build.pm and you will see why.

Plus, you would also have to change the Newest_Link field in the Category table to DATETIME, or modify the code in Links/Link.pm.

I think that the definitions of the system columns should be left as they are. I personally would not want to buy a plugin that changes my existing columns, especially if it breaks core Links features. This would be very unoptimal, as you call it.

Ivan
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Iyengar Yoga Resources / GT Plugins