I'm not an expert about AngularJS and we're still studying/experimenting with Alt, but AFAIK the combination is comparable, except maybe for the AJAX communication with the server - if Angular also manages that (which I don't know): with Alt you need to manage the server calls yourself, preferably by creating some API helper functions and calling them from inside the Actions.

EDIT: clarification

Thanks for your answer.

Angular have a specific service ($http) for that.

You're welcome.

By the way, when I did my research, I found out that some people are using React with Meteor, instead of Flux. That way, server synchronization should become a non-issue (but you need to like the Meteor way).