You learn something new every day. I have actually never heard of proportional pulse and had to look it up. I'm using a ranco at the moment but once I build the racks in the summer I may look at VE or Herpstat when the time comes.
I would say pulse is TECHNICALLY still on/off, but it adjusts a lot faster. true proportional is constantly running power, just at lower levals depending on what the probe is reading.