Yes Olympus has came a long way since the E-520 so an upgrade is a good choice. I can't speak for the E-PL5 but do own the OMD E-M5 and think it's the best performing compact on the market. The noise at high ISO is still an issue when compared to other cameras.
Just to toss an idea out there. E5s are selling for nice prices in the used market. Some under $1000.00 in mint condition. The E5 has a thinner AA filter and the images are super sharp. The E5 has a lot going for it still. Fast AF, articulating screen, weather sealed ect.
The only E-PLx I had I didn't like as the build quality wasn't good enough for me. Plus it lacks a viewfinder.