To Install, or, Not To Install

To my mildly geeky eyes, the defining difference between portable apps and regular ones is that portable apps are not installed.

I am a Firefox enthusiast, but was getting frustrated by often losing multi open tabs (I use session saver), after my wife would have several FF windows open, then close them in the wrong order. As she was impossible to train, I added Firefox Portable to my desktop HD, gave it its own unique icon, and use it exclusively, while she continues to use the original. I am careful to close my FF Portable after a session so that she can't mess with it. I have also briefed her (with some success) to close my FF and open her own (the original), should I forget.

Using FF Portable on my HD has the added advantage that I can clone it onto my flash drive, so that when using FF on another computer, I have everything exactly the way I want it.

As far as I can see, both programs work equally effectively, and there is only one tiny downside to FF Portable in this scenario. When I click on a link in an email, it will take me to my wife's FF, unless mine is already open. IOW, the original FF is the default browser, and my copy cannot be default because there is no reference to it in registry.

Based on my success with FF Portable on my HD, I am considering converting my email program from TB to TB Portable on my desktop.

My question is; Am I missing something? Is there any advantage to running "installed" versions of FF, TB, Filezilla, etc. on my desktop, as opposed to the portable versions?
kk