Decibel X reports max or peak. I "calibrated" it with REW so it's good enough for me. I'll run the same tests with REW later, but I don't think the result is that different.What did you track them with?
There are no phone apps reporting peaks for example,they only report max which is close to what you say (depending the music of course).
REW is a good way (that's what you saw in the post above) or a good real SPL meter which can report peaks.
Peaks are not only low,are also in highs too,some cymbals for example can cause big peaks (of course the recording is a factor but still... )
I really don't think that this lack of dynamics is a real problem with vast majority of hobbyists. But then again, for those who see it as important and have the money the 8381 might be one solution.