Do you have any good examples? I searched quick on Google, and most of those don't look too portable...
I only have the one I built for an example, was made of a half sheet of cabinet fir 3/4 ply. Drops in its place so it is unique to only that saw.
It's just short of 8 ft. so it can stand against any wall for storage, will lay on a work bench, across saw horses or can easily be transported outdoors to work or to other job sites. The area behind the fence is handy to place cut offs, measuring devices etc.
The only con I've found is a slight weakness in the saw area from saw weight but I've corrected that with a couple of 1x2 cleats on edge below that area.