The on-going maintenance is higher for an INSTEAD OF trigger, since every column addition or deletion, and some column changes, all requires changes the trigger, which is not the case with an AFTER trigger on only specific columns.
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".