The title says it all. The minimal code for trying it out is here: http://paste.pocoo.org/show/491320
Update: Seems it's all a matter of set(:inline_templates, file) being triggered when requiring sinatra before the hooks are in place. Requiring sinatra/reloader (which requires sinatra/base) before requiring sinatra solves the issue, however I wonder if it should be that way....
reload inline templates in classic apps, fixes #18
should do the trick, see https://gist.github.com/1286019.
But it has been fixed in master, so if you run against it, your example should work.
Good job, keep it up! :D