I bought a refurbed EPl2 last year and just went to the OM-D/EM-5 and love it. The EPL is still used for grab shots and there is nothing wrong withi it, but the OM-d is such a better low light performer. If you're not into carrying lenses and such, stick with a good p&s. I have an old canon G10 that's still awesome and can only imagine how awesome the G15 is, however it is about $125 beyond your budget. I used to shoot Nikon dslrs but always preferred canon for compacts. The menus just seemed more intuitive for me.
I love the 4/3 system, but if you buy a mid line camera with the kit lens, you won't see much if any improvement over a good p&s and won't have the convenience or compactness either.
Have a look here