You may have something very granular or customizable planned in terms of your scripting effort so this may not be applicable, or these options may not satisfy your requirements, but I figured I would throw them out there since they were not mentioned and they may save you some time:
1. sp_updatestats (SQL Server 2005).
In SQL Server 2005, sp_updatestats updates only those statistics that require updating based on the rowmodctr information in the sys.sysindexes compatibility view; therefore, preventing unnecessary updates of unchanged items.
2. SQL Server Index and Statistics Maintenance by Ola Hallengren
Setting the UpdateStatistics parameter to COLUMNS, the OnlyModifiedStatistics parameter to YES and the StatisticsSample to FULLSCAN or SAMPLE you can have it only update stats that have changed since the last stats update, and with a sample size of your choice.
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--Plato