I think you should upgrade only when you are thoroughly are dissatisfied with a component, or no longer is able to meet your needs?
A set of new speakers will satisfy for a while, but, in time, the itch will return?
You should compare the speakers in the same acoustic space at the same volume level and preferably under unbiased circumstances. Even though speakers will sound different, at time a whole lot or just barely, bias or other features than sound may steer you to the wrong set.