well firstly, the joomla-smf plugin is not the product of joomlapolis, but of joomlahacks, and they both provide different products that serve different purposes.
secondly, the option for cbe is so that cbe users will be able to bridge smf with their joomla installations too (which makes perfect sense from wolverine's viewpoint)
If you ask me, there is no debate as to which is better. joomlapolis has made a very wise move in the implementation of the plugin system, and this would have been impossible without the technical expertise of the core CB team. The other major factor, of course, is the sheer numbers of the community.
