I had an exhaust jack years ago. It was great, easy to use and safe. It hit the exhaust pipe one day and got a hole in it, so that's one issue. Other issue was it tended to become dirty from exhaust gas, which is pretty yucky stuff. But it always worked great, gave plenty of height and always felt safe.
I just have the standard patrol jack and a block of wood, like MB now. If I need to go higher, I use more wood.