Hi Gareth,
Better late than never.
If you are developing a desktop application JavaScript views IMO are the way to go.
Desktop applications will more than likely require lots of views. The views may not be form based and may need dynamic content or use conditional rendering, use data from multiple models, from multiple backends, use controls from multiple libraries.
I know that all of those things can be catered for outside of the view.
For me the compelling reason to use javascript views on desktop applications is I can debug the code at runtime, seeing the code allows you to quickly understand the intent of the developer when it was written.
cheers
jsp
This blog is worth reading http://scn.sap.com/community/developer-center/front-end/blog/2013/03/19/how-to-build-testable-sapui5-applications