I could see how it is both useful and could have a disproportionate, negative impact on lower social-economic classes.
Not sure if there has been any research, but yes I have heard on the radio how some people are against the express lanes because it does have a negative impact for those who can't afford it, and it's quite dangerous.[1] The latter might be due to a bad implementation however.
[1] https://www.kairelaw.com/car-accidents/lane-diving-make-i-95...
IMHO MnDoT has actually been doing a pretty good job over the last 15-20 years at smoothing out traffic flows considerably in the north metro without adding much in the way of metering/tolls. SW Metro traffic flows still suck from what I hear, although to be fair the topography has something to do with that (i.e. HOW many bridges do we need to build over the Minnesota River?)
I remember reading a while back about a European city that was using it with great success. I don't remember which one though.
I think the algorithm there is probably similar to this one and would ratchet up the price if a slow truck/construction/plow created a condition that looked like congestion.
I've heard both ways, that it helped considerably and that it didn't. (Because London doesn't have many through roads and few vehicles were there that didn't have to be?)