To clarify a few points:
- The nature of portable copy of NVDA: it is identical in shape and form to the installed copy of NVDA except for two things: it does not have special privileges (no audio ducking, for instance), and user configuration folder is stored in the same location as the portable copy directory. As installed and portable copies are identical, portable copies DO support updating to a newer version of themselves.
- Creating versus updating portable copies: you can create a portable copy of NVDA in three ways: when launching NVDA installer, NVDA menu/Tools/Create portable copy option from installed NVDA, or via command-line. These options do provide an option to start the just-created portable NVDA after creating it. This is the method Brian is talking about, whereas Gene and I are talking about updating portable NVDA once created.
- Answering Howard: yes, you can create a portable NVDA anywhere (removable media and internal storage included) except locations where you must be granted admin privileges and on optical media.
While I have an alpha build of NVDA installed on my computer (for development and testing reasons), I have portable versions of beta and stable builds, as well as an alpha build containing add-ons registered on community add-ons website to test add-on compatibility. I do run and update portable copies from time to time, more so for beta builds whenever new betas or release candidates are released. I keep a stable version handy to replicate stable version experiences and to test various add-ons.