Is there some reason the other direct sampling RXs perform better?
Doug, it is not because "other" perform any better. It is because "Sherwood says" they are better"
"Sherwood's" approach looks suspicious and that is what Pibo (+1 to him of my support) means mentioning "Sherwood's reputation".
Some test conditions that are wrong in this case?
Sherwoord's whole concept (mixing analogue and ADC-based TX/RX into one testing) is wrong. Apples should be to apples.
This type of measurement should not be dependent on the software version, v2 or v3.
Really? Same as to measure your car performace with 2L and 4L engine and then say "nothing has changed" ... in the rear doors.
Actually, to get proper measurements with v2 and v3, the reseacher - first and foremost - has to completely understand the difference between v2 and v3, otherwise the "measurements" will result in waste of time..
The point is, EE should take his results seriously, and try to reproduce and understand them, and improve the results if possible either by test condition changes or design changes.
Are you proposing EE to educate "Sherwood" about ADC/DDC basics? Would be bloody waste of time (IMHO), but ... well, "Sherwood" may sit (as a student) in the classes, which EE are performing (as the professor) in the local Universities ...
Doug, most of EE customers prefer EE to continue working on the software and future hardware, rather than merry chase improvment of the "place" in self-proclamated "expert's" ratings.
And as for the measurements, we have enough educated enthusiasts in the community to perform the measuring.
V2 already completed, Pibo already have given you links.
V3 will be measured sooner or later, once final release of V3 will be out.