I've heard the Sonics analogy. I just think it's a very different situation. Whereas Sonics fans have every expectation of regaining a franchise and even take offense to the OKC team merely observing the Sonics' retired numbers, the Expos fans as far as I could ever tell embrace the Nats. Moreover, the Nats, by virtue of tributes to Expos greats in the Ring of Fame, have embraced the franchise's origins. I'm one of those who thinks that's the right way to do things.
***EDIT***
Dang, I just realized... not sure how conscious the designer of the current jersey was of the connections to both the Expos and, too, the Negro League Grays, but I wouldn't doubt that s/he was altogether conscious...
The Grays unis, for the most part, featured the middle piping down the front of the uni.
Then, the Expos original unis placed the team logo on the player's left side, and the number to the right.
Both of those, of course, are ALREADY consistent with the Nats' home unis. (Granted, the W on the left once appeared as part of the Senators' jersey, but as far as I can tell, never so the number on the right.)
To be honest, I gave the "pinwheel" cap a passing thought, and then, perhaps changing the font of the jersey numbers to replicate the Expos'. But I have to admit I always thought the Expos' pinwheel, while unique, was too much so. I was much more intrigued about the numeral font, but even then, I just have a visual preference for those block numerals.