but overall I think I was happier when canon was in flux and anything could happen.
It's funny, but when I read that, I thought, 'Yes.' I've felt the same way too, and I've struggled to put my finger on exactly why. For me it's a combination of one of the things you mentioned--the need to incorporate canon events so fully-- along with ignoring the brouhaha over how the series ended.
I was intrigued by what you had to say about collaborating--I'd noticed that you'd done it in the past and was curious about what you'd have to say. I think what must be essential is that both of you are strong writers--it's interesting to me that you are able to do this with others who see things the same way, and those that don't.
Happy writing for the games--I'll be looking forward to your story!