Why do you want to replace the G3? What doesn't it do that you need it to do? In what ways does it limit your photography?
Many of us have a tendency to chase hardware looking for big gains in our photography when, in fact, the body is frequently the least important part of the equation.
Would a new lens make a bigger difference in your images? Or maybe a photography course, or some books on photography?
The G3 is very capable of making high quality images. Will changing bodies really make a difference in your images?
I've stopped thinking in terms of "equivalent" focal lengths on m43. 25mm is what it is, and what it might be similar to on some other format doesn't matter to me any more. We need to learn what to expect from our current equipment, not keep mapping it to the old. No one refers to their 50mm FF lens as "equivalent to 80mm on MF."