I brought my cuttlebug to a friends house the other day. It was so easy to transport. It has a handle on it & the sides close up for travel. I measured the section you put your paper through and it is just shy of 6". I don't have any other die cut machine, so I can't compare it to others, but I did a bunch of research before I chose the cuttlebug as my machine of choice.
As for your question about the Nestabilities. I have all of the rectangles, ovals and the plain circles and squares. As soon as I get the money, I plan to invest in the scaloped circles and squares. The rectangles are what I seem to be using the most. They are great for embossing card fronts, cutting out windows and overall layering. I got the rectangles first because I thought they'd be the most used & I was right.
JIL