sure why not

I made a straight trade, essentially: eM1 and a couple of lenses for K-01 and 18-50re (both white!).

What I lose:

• weather+chill sealed body
• some compactness
• a complex menu structure
• PDAF focusing

Do I gain? I believe I did!

• a very familiar Pentax operating system
• a camera that can use Very small DA lenses (DA40+70 on hand) with no adapter!
• a 'casual' body that looks silly not serious
• flash available at a button press

And the similarities are good ones:

• decent image stabilization inside
• acceptable HD video with optional mic input
• spare batteries on hand

The loss of weather protection is covered by the S5, so one camera it another can compensate. 

Once again, my keeping Pentax lenses around drags a PK body back into my kit. I looked at a K200d, but the K-01 also has happy memories, and a more up-to-date sensor means nice results and simple video. Nothing magical by modern standards, I grant you, but still respectable dXo test results - far higher than the eM1 could manage with its smaller scale.

Should be a fun team. 

And most of the Pentax lenses will serve time on the S5 in "classic" manual or A-priority modes.