Magento: How do I put widgets into a layout xml?
Turns out, it wasn't inserting any meaningful data because it wasn't receiving its parameters. It needs non-standard parameters to be set through action tags:
<block type="enterprise_banner/widget_banner" name="hero_banners" as="hero_banners" template="banner/widget/hero.phtml"> <action method="setDisplayMode"><value>fixed</value></action> <action method="setBannerIds"><value>4</value></action></block>
Since the topic has already been solved, I have an off topic solution
This could be set as a block within a .phtml file if required.
<?php echo $this->getLayout()->createBlock('enterprise_banner/widget_banner')->setBannerIds('4')->setDisplayMode('fixed')->setTemplate('banner/widget/block.phtml')->toHtml(); ?>