One thing that seems like a potential deal-breaker for some, unless I'm missing something, is the incompatibility with server-side expression language or templating syntax used by Java's EL within JSP files and Grails' GSP files. Does anyone know if there is the option of defining a different wrapper then the default ${} provided with this templating engine?

It would obviously only cause issues with JS contained within a server-side parsed file, but that could definitely cause enough disincentive.