I have tried it. As I said, I've done it with Reaper. While it is nice, it really isn't that much more efficient for me than one monitor, it just looks nicer. And costs a lot more and takes up a whole lot more desk space. If you think it is impossible to use a DAW efficiently with only one monitor, than maybe it is your style that is messed up and not the DAW, because there are many, many people who work just fine with one monitor.
What I'm saying to use is that it would be a worthwhile complaint if everything made it Reaper came out sounding like crap, but discounting it just because you don't think it works with your two monitors (it does, btw, b/c I've done it) is a pretty dumb reason. If someone gave you a Ferrarri, would you say, "Sorry, I don't want it because I can't see out the back very well"?
Sorry for my rant, but it sounds to me like you opened it up, noticed it loaded on one monitor by default, didn't touch anything at all, and then got rid of it. That's a very poor way to run a trial.