Bernard
I can't answer your question, but are you aware that PTGui is now available for Mac?
Some time ago I tried several trial versions of Realviz Stitcher but in my experience they were all unstable. (yeah, yeah, I'm on Windows......).
On the other hand I've found PTGui to be stable and is now capable of doing everything I need, including multi - row panos, 16 bit output, layered .psd file output, etc. I'm also able to include bracketed shots in the mix and it will automatically stack them on top of each other. It will then output a layered file for masking in Photoshop. I've output a few .psb files recently which have been close to 4gb.
On top of all this it's a lot cheaper than Stitcher. A trial version is available at
www.ptgui.com .
Highly recommended.
I have no connection with PTGui other than as a very satisfied user.
Regards
Frank