Your current stem has a rise to it, as do your bars. Going with a shorter stem and flat bars will drop your grip height quite a bit, especially if the new stem does not have rise built in. Not trying to tell you what you do or don't want. Just giving you some food for thought. 

Usually the trend is to go longer stem with flatter bar for more stretched out, forward weighted, XC race type setup; or shorter stem with riser bar for more of a back weighted and/or upright riding position that feels more comfortable and confident on descents. Shorter stem with flatter bar just seems an unusual combination of changes.

Another important measurement to consider when changing out handlebars is handlebar width.

What are your reasons for wanting to change the cockpit setup?

Unless you have a very specific setup/geometry in mind. It is probably best to change one thing at a time that way you can evaluate the effects better (scientific method). I have a riding buddy who tends to change every suspension setting all at once, just before our big rides in Pisgah...  I would not recommend this approach.

I would recommend starting with the stem and going from there.

Im doing similar and asking contributing questions in other posts.

Bud is spot on and as always a good contributer with his upright vs lay down approach.  Another good rule of thumb  / observation is the ratio of angle from seat height to bar height.  ie bars above, level or below seat level.  (thus affecting the severity of too much change.) Your going "double down" on changing both rather than one at a time and hence minimizing that severity you "might" see.  Not totally accurate, but looking at the pic seems as though your bars are possibly a little above your seat.  As you go down you will notice changes.

Bottom line, to support Bud, change one first, because you may immediately notice unwanted change before you go extreme.  And then there is the inverse you already noticed...  If its not broke, dont fix it! ;]

My scenario is I am more of a lay down XCr.  But Im building a new rig and its std build out components go for more of that extreme upright.

Trying to find local parts to "try" iterative to accomplish the same and try the recommended upright geometry the bike is designed with vs my usual and see if I like it better or worse.