I guess if you could give me the alternative implementation, on a platform that you had some guarantee would last longer than PL/SQL, then you could compare. But I don't think there are any guarantees. You're going to have to migrate in time, no matter which way you go.
My 2 cents, would be that you should code to your shop's strengths. If you have plenty of PL/SQL developers, invest in PL/SQL code. Mostly .NET ... code a business layer in C# or
VB.
--=cf