They aren't the same lasers as RPLs, there are some differences. Not to mention its DX. When I buy lasers like this, I have to sell some at lower specs than they are rated, and RMA others because they don't meet spec. If one of those 20mW lasers were broken, putting out 0mW, you think DX would even check? Nah, they'd send it to you anyway. And if it only puts out 10mW? Well, then you're screwed, paypal won't help you - I found that out the hard way.
I sell similar units, tested (my Oceanus line) that aren't much more - in fact my 5mW blue is cheaper, and my 20mWs aren't much more than 10% more expensive and come with more things. And, they're tested. If you want even better, you get a much better warranty service through optotronics for a bit more on top of that.
So its up to you. I gotta say though, if I were spending several hundred dollars, yes, I would pay the extra cost to get the benefit of not dealing with a company we all know advertises fraudulent specs more often than not.