Two years ago I traded in my heavy traditional SLR gear for what is called a Micro 4/3 system camera from Olympus. I have not regretted it one bit. The Micro refers to the smaller camera bodies and lenses. The image sensor is the standard 4/3 sensor found in the bigger cameras that use it.
I can put a camera body, extra extra battery, 24-80mm equiv. f/2.8 lens, 150 mm equiv f/1.7 lens, flash, and a polarizer filter in a package no bigger than a child's lunch box. Both the weight and size are at least 1/2 that of an equivalent systems using 'D' sensor camera like a Nikon 3100 or a Canon Rebel.
Image quality? I routinely make 16x20 prints that look great. Lots of detail.
Olympus and Panasonic make camera bodies and lenses, and they can both be used with each others equipment so I have a great choice in equipment. Of course, there are 3rd party companies that also make lenses for these cameras. Overall, it's very nice way to travel.