Hi Keith
What I said is for now but I believe in future it will get better.
I've done three project in vision and in the end I personally use perspective in every case now but I face a lot of problem with perspective in regard of performance. For example consider opening and saving a view. Vision is much faster in my experience it is at least 3 times in best case.
The vision drawing tools is really nice and also you can deep into any svg object in object tree but instead in perspective you have to find the svg element you need in DOM element tree which is very hard and time consuming .
Working with nested container is really laggy and hard specially when double clicking on object doesn't work for first time.
If you have an template in vision window double click on it open the source but in perspective for embedded view you should find it on view tree and open it.
Even switch between open views in perspective take a lot of time.
Lastly I face new problem with embedded view as you already know. Now I have to redesign my view to make my embedded view as low as possible.
Don't you agree with me?