I and a testing partner independently discovered a problem with drag/drop yesterday for a common use case that can result in a silent failure. As a result, I can’t recommend that approach until McNeel addresses it because a non-expert user who isn’t being extremely attentive probably won’t notice the failure to install and will then conclude that the plugin is defective.
The explicit approach via File->Properties->Plugins-Install button doesn’t suffer from this problem in the case of a raw RHP.
Even for internal tools, at this point I’d recommend packaging via YAK and the McNeel Package Manager: it’s the genuinely supported path for both install and uninstall.