The new "auto update" for v.3.2.0 is welcome, but (on a PC) it forces installation to Drive C: which is a pain as I have my previous installations on another drive.

Do I now have to migrate SD to C: or is there an option somewhere to install to the existing folder or a drive of choice?

Are you aware that Windows offers a supported way to move your Program Files directory to another drive, or change it? I haven't used it myself, but if you want all software program files installed on a specific drive it would make sense to actually use that feature instead of having to change each piece of software during the installation process.

SkyDemon is a portable app; it doesn't rely on the registry for its settings and behaves as a good Windows software citizen in terms of storage locations for settings and user documents.