I think the number one reason people have trouble with Clusters is they slap it together without doing a lot of research and study. A cluster is much more than just a fail-over SQL server scheme! For some it may be their first experience with Advanced server, SQL Enterprise Edition, Microsoft Clustering technology, and fail-over logistics. Not to mention clients that think since they spent $$$ dollars on the setup it will be more stable and require less labor than monolithic configurations.