you are right to ponder over the EVF.. I have the 5N with EVF.

Issue you will face is your style of street shoot.. do you point and shoot of take time and frame..and since you also prefer prime.. I trust bokeh and subject control will be you prime concern... for that EVF is an asset.. if you just shoot using wide angle, then EVF is not much of a use because you dont really have the time to wait for the critical moment and depend on all the auto to give you the freedom of composition.

what i did find is the 5 EVF has some critical attributes the 6 will not have.. It is swivel.  That means you can shoot from waist level - a much more interesting angle than at eve level.. more so when using 50 mm prime.  The bad side is it is fragile but you will learn how to take care of it.  There are times I wish I had the 6 but I am sweet as using 5 with and EVF attachment. 

Study your work flow and you will  know..  I use a full manual Prime and it is much faster and use less power too..