My experiences at work, I run all newer saws, bosch, porter cable, rigid, makita. None are setup with left side blade but we are a concrete company so these saws are not used all day long and it's not tough to deal with it. They are not babied, all ARE abused.
Rigid, absolutely hate it. The size seems compact in comparison to the others but there is not a noticable weight difference. For me the angle of the grip is terrible and causes discomfort in my wrist with any extended use. Doesn't seem to run as strong off the generators as the other three either.
Bosch, they seem bulky, are definitely the heaviest out of the four but they perform very well. Have good power and easy to use.
Porter Cable, this things a true beast. Feels like the lighest and cheapest of the bunch but when you hit the trigger there is a difference between the others. I think some of the cheaper feel might be the saws bottom plate being composite instead of a metal, it does not lose its stiffness though. It seems like it takes a lot longer to get the blade up to speed but once it is it flat chews wood, nails, etc. I actually keep a spare old blade for this saw to put on for cutting out holes in the subfloors splitting the top of the floor joists in order to get concrete chutes into the basement. It is nail after nail plus ripping the subfloor glue on those cuts and the saw never flinches. If I had to guess this saw has the most torque.
Makita, this saw seems to be the caddilac of them all. Very very smooth operation, by far my favorite. When I bought this saw I wish I would have opted for the magnesium version just for the added weight reduction but overall this saw has impressed me more than the others I have.
I have run Makitas and Dewalts as well but honestly I would go back to the Makita. The blade stop on the Dewalts were very very nice though.