External versioning (external or external_gte)

It seems that this question was asked (but not answered) some time ago as well

In our case we have database where every entity is versioned. Can we use this entity version number with external_gte?

It's seams that using external_gte would work for us because we can easily "Reindex" entire database when we suspect it got out of sync with ES index.

Do you think we miss something in our understanding?

Mirek