NSIS
If you build both ia32 and xha arch, you in any case get one installer. Appropriate arch will be installed automatically.
Windows requires to use registry keys (e.g. INSTALL/UNINSTALL info). Squirrel.Windows simply uses application name as key. But it is not robust — Google can use key Google Chrome SxS, because it is a Google.
So, it is better to use GUID.
You are not forced to explicitly specify it — name-based UUID v5 will be generated from your appId or name.
It means that you should not change appId once your application in use (or name if appId was not set). Application product name (title) or description can be safely changed.
You can explicitly set guid using option nsis.guid, but it is not recommended — consider using appId.
