Yeah, I think that's what I keep coming back to. If everything else seems to work without a hitch then I don't really think that the output of rtl_test is the end all be all litmus test just because it says you are losing bytes here and there. If everything else is working with it software wise except that one issue you are having in DSD, then it makes it very difficult to say for certain that those two things are correlated. That's why you need another computer to test this on.
I think what kind of makes it frustrating to test to be honest is that you only have one computer. I don't know how you live like that

I can't bring myself to toss out working machines if they have at least a Core2Duo or higher in them. I can always find some use for them, even as a lowly file server or media center or something. I recently literally had to force myself to toss out 5 Pentium 4 era computers that were taking up too much space on my shelving area.