Little but speculation from all sides as I see it.
Until someone actually bench tests these things, it's all a 'who do you trust' game. If Nagra is not simply leveraging the historically well deserved goodwill value of their name (as yet undisputed for them, yet the trend towards doing so is increasingly common with plenty of other 'famous quality' brands across a wide variety of alternate market segments), they would do well to back up that good reputation with solid justification: explain in detail the actual differences, show the differences in specification, show resulting test data, perhaps even offering sample comparison recordings. If serious about persuing this relatively new market segment (for them), Nagra has plenty to gain, and little to loose in doing so, unless things don't stack up.
The onus is on Nagra to demonstrate their identical appearing recorder superior in ways other than name brand reputation. If they choose not to do so, their reticence and silence speaks volumes IMO. The suspicion is already out there and apparently growing. They need to do something about it. Supporters begging others to "trust them" is not them doing something.