Check back in coming days for more details.
Store.js will soon have pluggable support for localForage (either by implementing similar functionality in separate storages, or by simply adding a pluggable storage which uses localForage under the hood).
There are a few benefits to using store.js, such as full cross-browser support and useful plugins, but the biggest meaningful value-add over localForage is probably the availability of a synchronous API that allows you to read and write values without callbacks, promises, etc.
In my experience you only want to use asynchronous APIs when you have to, since they add a fair amount of complexity, are a common source of errors, and are harder to debug properly.
But yeah, check back later and you'll likely find that store.js supports the same storages as localForage, in addition to the its other functionality.
There is an active issue to add the async indexdb/websql storages to Store.js (https://github.com/marcuswestin/store.js/issues/181) so that they can be used when needed (e.g when you need to store many tends of MGs of data), but for 90% of your use cases the simplicity of the synchronous store.js API may likely save you a meaningful amount of code and callback/Promise/stack trace debuggery :)
Thanks for taking the time to make the case!
The other requirements localstorage alone can't address.