I read on an old none commentable reddit that Tpope no longer uses his vim-repeat plugin, and instead uses g@. I have used g@ in plugins, and unstand you set opfunc first, then g@{motion} will run opfunc on the motion.
I have had some success using g@ when editing to repeat a titlecase function, but havent figured out how to repeat for example vim-surround functionality with it. Does anyone find it useful when editing text (i.e. outside the context of vim scripting).
g@ is extremely useful for plugins and custom maps, but it's not so useful by itself.
One reason is that opfunc, which is a global option, needs to be set correctly before you type g@. Theoretically, you could use :set opfunc=MyFunc followed by g@ but you may as well create a mapping wrapper which does :set opfunc=myFunc<cr>g@ since then it works regardless of what opfunc was set to before.
Generally, a plugin which adds operators should use g@ so that repeating with . works. Likewise, a plugin which adds "whole operations" should support repeating by using g@l or similar.
Since plugins should be designed to allow repeating via ., there is no need to use g@. It is unlikely that you can repeat a plugin's map via g@ unless it was designed specifically to allow that. But in that case, the plugin would likely be designed to support . repeating.
vim-repeat exists from a time long ago. I don't know of a case where g@ won't work but vim-repeat will (but might be wrong). The one advantage it still has is the interface is a bit nicer for plugins to use.
@ginstead ofg@in the title and the first sentence of your question and if I understand properly that is a typo (which would be worth editing to avoid confusion). Could you also link the Reddit post you are referring to just for my curiosity please?vim-repeatfor old scripts. 2. He tries to avoid the plugin for future scripts in favor of opfuncs (and he may refactor some old code to get rid of it). 3. He's right; the plugin has bugs, which native repetition can fix.