My main concern - how does application state get handed off to the client-side code after the initial render? Sure, it's nice to have some pre-rendered templates, but at some point it needs to "transition" cleanly to the client.
I just started hacking on Rendr last night, so I don't know if it shares state between Express on the server and the client-side app. My guess would be that Rendr does not have this built in as it's stated design goal is to stay small/modular.
(author here) We just bootstrap some JSON onto the page to transfer application state to the client. It's the same approach as the `express-state` (mentioned in a below comment). Same as any client-side app.