<p>We have been using the Client Access ODBC drivers when accessing AS/400 data from our .net applications and SQL DTS/SSIS packages. Are there third party drivers that provide better performance or functionality?</p>

I know this is on the other side of the hill, but I've been using
JTOpen
as a JDBC (well, Java ...) driver in a previous project. This is an OpenSource version of the
IBM Toolbox for Java
. As such it is usually some versions ahead of the IBM release and had fewer bugs. My experience with this driver was very positive.