well I am familiar with automotive clears. The current ones are all pretty water clear. Older ones like deltron , had a tinge to them. The new stuff, at least that I use ,, is crystal clear,,, I use PPG 2042, Randy uses Omni and seems to like it pretty well. I cant say as to its clarity but I am fairly certain its pretty good.
The way to tell is to take the lid off the can and look into the dclear. you can tell how much yellow it has.
As for water Urethanes, as in woodworking urethanes? They really arent made for what we are doing, I dont have anything to say about them. some people use them, I have no interest in exploring them for the reasons stated
When comparing Dope to Urethane, you need to remember that Dope is only about 12 percent solids,, and urethanes are typcially 40 to 50 percent solids. So you have to put on like 5 coats of dope to equal one coat of Urethane