I have looked at the one2edit website, and it looks as if it is the kind of application I am after, you said that it was available as a SaaS, I would like to know what the costs involved are, and whether this could be used in a web application where clients could login and add artwork and send the template for approval. Regards,
CHILI Publish offers indeed a perfect solution for what you are asking:
1. create a template in Indesign
2. let the end user edit this document online within boundaries.
Big advantage of CHILI Publish according to me is that they are not relying on Indesign server, they have developped their own engine. No queueing, no lag when editing... This results in a very nice user experience.