[Brightcolours]

Here's a more or less fair comparison of fully equivalent setups:
MFT vs APS-C vs FF
 
http://j.mp/2qohuve
 
As you can see - almost no difference - as expected.

Note: The Pentax lens is actually a little "longer" (equiv. 375mm) which is why it is a little bigger.
 
Pentax 60-250mm f/4 (x1.5) = 90-375mm f/6 
Olympus 40-150mm f/2.8 (x2) = 90-300mm f/5.6
Canon 70-300mm f/4-5.6 = 70-300mm f/4-5.6
 
Same quality league.

The small Panasonic set up is about 1/3rd of slower than above mentioned APS-C mirrorless from Canon and Sony, not that big a deal when shallow DOF was not something to look at to begin with.

If you want to make a real equivalent set (not really the purpose of this thread?), skip that Pentax and insert a Canon or Nikon 70-200mm f4 on APS-C. I'd like to show the Nikkor in the comparison, but the site does not offer that lens:
http://j.mp/2pBalVz