I have a winch-mount version, it's mounted on the truck so I can't check the weight but there is no way the ARB winch mount bumper is anywhere close to 137lb, I would bet money it's less than 100lb out of the box, especially without a roller fairlead installed. I would imagine the non-winch bumper would be close or slightly less.
I took some photos with rough tape measure measurements from the center of the hubcap to the lip of the fender flare, based on those photos it appears I only lost about 1/4" & 1/2" ride height (DS & PS) on my tired 25 year old OEM springs, but then again I was eyeballing the center of the hub caps with the tape measure end so the error bars on my measurements are at least that much, which is probably why the two measurements differ. It looked fine so I wasn't too stressed about it, plus I'd phoned it in on the initial measurement and there was no going back.
IMO you don't have to worry, even with a stock suspension. When people throw a big winch in there, that's when you gotta worry.