Easy Populate 4 works fine for me on 1.5.1.
I also notice that an earlier version of Easy Populate we've used in the past in now 1.5.0 ready; I expect it would also work with 1.5.1. I may test this one soon, as with Easy Populate 4 one can have it installed along side another easy populate and each might offer a strong point.
But before I'd do anything I'd first install DrByte's data base backup/restore plugin and use it to backup before any easy populate import. The easy populates work just fine in our experience, but operator error can sometimes creep into the spread sheets.