[This was written before the reply directly above was posted, so it's in reply to the message before that.]
PortableApps support has been in the beta versions for about a month, if you want to try it now. It'll also be in the 10.0.5.0 stable release which we plan to release in the next week or so.
However, it probably won't do what you want. It's still for running a portable version of Opus off a USB device. The PortableApps support means we hook into their menu system and write Opus into the folders they expect apps to be written into. It does not remove the need for a USB device to be used (or act as a dongle) for portable installs of Opus.
You can use the "use this device as a dongle" option to allow you to write a portable install to a harddrive or any other location. The designated USB device will still need to be plugged in for the portable install to work, but it removes the need for the actual files to be on the USB device (so it's as fast as running a proper HDD install, but mainly to allow people to put Opus into encrypted devices which exist on the USB device but appear to the system as a separate drive).
All portable installs have some compromises in how they work, though. Although we've recently made it so that Explorer Replacement works with portable installs one you launch them, it still obviously cannot work with them before they are launched (since it requires registry changes).
We still believe that it's best to install Opus normally on your main machine. The portable versions are best used when you want Opus to be portable.
I'm not sure what you'll really gain by being too paranoid about allowing programs to be installed normally on your machine. That seems more likely to create problems which require solving and use up your time than the possibility that installing something normally might do something which causes a real problem. Don't get me wrong, I worry about those things with new or untrusted software as well, but I try things out in a virtual machine first and if they work well, I let them on my main machine. If they don't, I roll back the VM and forget about them.