Dell (via USC) unpacks specific drivers for both RedHat and Suse to use after installation on its servers. As Ubuntu server isn't officially supported, this clearly isn't happening for Ubuntu.
Is Ubuntu server then running with native drivers? In that case, which drivers are native with Ubuntu, and aren't (e.g. are Dell replaced) with RedHat/Suse? Are dell optimized drivers available for Ubuntu somewhere? Can the ones for RedHat or Suse be used with Ubuntu?
Are there disadvantages of this lack of fine-tuned drivers, and if yes, what are they? Would they make the switch (and extra costs, as both RedHat and Suse Enterprise aren't cheap) away from the free Ubuntu server worthwhile?
Dell recommends Canonical's commercial support for Ubuntu server on its machines, is this recommendable? Do they offer fine-tuned Dell drivers to replace native drivers?