NSIS 2.42 plugin handling

Could I please get some clarification on the new plugin handling introduced in 2.42?
Which one is true (if any):
1. A plugin stays loaded after calling and is unloaded before installer exits.
2. A plugin is unloaded after calling, unless it specifies that it needs to stay loaded.
If 2. is true: since /NOUNLOAD is deprecated, is there no way to force a plugin to stay loaded?

if you implement the new nsis function export in your dll, it will stay loaded, if you don't, everything is like it was in 2.41

I'm not a plugin developer, I was asking as a scripter. You say that plugins which don't utilize the changes in plugin api are treated the same as they were before, which means that they're unloaded unless script says otherwise. I did some testing and I've seen for myself that it's true - 'old' plugins which require to stay loaded (e.g. NSISArray, Stack) still work fine, unless you remove /nounload from their headers. So /nounload and SetPluginsUnload still work, and I had thought they were completely obsolete since they were removed from nsis documentation. As for updated plugins, System for instance, they don't respond to /nounload and can't be forced to stay loaded. Or maybe I'm wrong, but I couldn't get a locked system.dll after installer exit (👍 ). I guess I should've done this script-fiddling before posting my confusion. But perhaps someone else was wondering about this and that's why I'm so elaborately answering my own questions. 🙂
I have another question, though: I used to use /nounload with System even when it wasn't necessary - specifically, when I had it called many times in a script, to avoid repetitive loading and unloading. But I haven't seen anyone else do that and now it's not even possible, so, did it make any sense or can nothing be gained by such approach?

I used to do that also (/NOUNLOAD for everything except the last call), but now system plugin stays loaded always, so there is no point in doing that

So System always stays loaded... I like that.