Well I *had* a nice long post written on this subject but I lost it all when my 30 minutes of airport network time expired. Amster-DAMN!
...sigh...
rather than rewrite, I'll sum up and you can imagine just how compelling the original post was.
Fusion architecture is about leveraging capabilities that were designed to work together to build solutions. Integration architecture is about designing capabilities that need to be leveraged in order to have a solution.
Support, stability, deployment times, coding load implications should be obvious.
Don't get caught in the flexibility trap. Integration architects will often play up the necessity of flexibility in solution design. But that is a slippery slope. It's important but be careful where you stand. After all, the most flexible tools are a compiler and some machine code. But really, who wants that?
