So if you reviewed that percent variation at a set power output multiple times over the course of time, a change to the percent difference would not be reliable to indicate chain wear, lack of lubrication etc. ?
I calibrate all my power meters based on my Neo. I’d say that Neo should read lower than whatever reads before drivetrain losses. My Stages differed about 6,5%, I believe most of this is due to the fact that I have leg discrepancies. But my 4iiii read about 3,5% lower.
Would a chain wear measuring tool and inspection of the drivechain not be just as easy a way of checking for wear? Run your finger along the chain or listen to the noise it makes check if it needs lubed? I just think there are easier way to check these basic issues we all face as cyclists and we don’t need to be worrying about using two separate power meters to see if our chain is worn.
It would be nothing but marketing hype. You only have to read the thread about ceramic jockey wheels to see that.
The stated tolerance on the power readings is likely too large to reliably get what you are asking. It might work as you want, but there are easier and more basic ways as Andy says.
These trainers and meters just lack the precision that some want for “testing and evaluation” purpose for more than curiosity level analysis.