When developing a web site in a CMS, the initial setup is easy, the entry/use of the built in and add-on modules are good, but anything 'out of the box' causes some significant work and work-arounds. As with most other projects, 80% of the cost is implementing 20% of the project.
I recently become a CodeIgniter convert - and have been looking into Expression Engine, a CMS from the same person/group that brought use Code Igniter - Ellis Lab http://ellislab.com/. The interesting thing about this CMS is that it's not all-consuming. Unlike the others that try to be the entire website, Expression Engine is being geared towards (especially v2 which is being built with Code Igniter as the foundation) an add-on...so, you can either have the cms manage the main site and utilize Code Igniter for those area requiring special coding OR have Code Igniter the main site and use the CMS for the static content areas (this is my interpretation).....WOW - keeping a tool to what it's good at and allowing integration with other tools...not a new concept, but one difficult to implement.
I'm looking forward to 'playing' around with Expression Engine more - getting ready for the 2.0 release - and seeing if the 'Jack of All Trades' pattern to disaster will take hold and bloat the Ellis Lab team's work out as it seems to have done with the other CMS's on the market.