Rawfa,
I shoot with a GX1 (and GF1) and mostly with the 20 1.7, 45 1.8, and 14-45 zoom. I can't speak to dynamic range. Other system features are more important to me, so DR is what it is.
I do feel, though, that 3200 will be a stretch for any current m4/3 system, likely including the OM-D. I routinely shoot at 800, and 1600 in a pinch. If good 3200 noise performance is really a need, you should review online samples.
As we all know, every system has trade-offs, but I think m4/3 strikes about the best balance between size, lens options, and performance.
John