For ages, I used a Canon 40D + 17-55 f2.8, 70-200 f4 L IS, 10-20 Siggy, 50mm f1.8 mk2, and with a GF1 + 20mm f1.7 pancake lens as second body. The quality from the GF1 was never worse than any of the shots from my SLR I found, and it was a much smaller package.
I've always wanted to upgrade...