Another "game changer" came out last week, this time Zipp's new 454. The primary porpoise (yes, there will be cetacean puns, it can't be helped) of the new design is to reduce steering force input from cross winds. From what I've read to date, the benefit to outright speed is minimal, it's just handling that's been substantively improved.
The 404 Firestrike had some small aerodynamic improvement over the 404 Firecrest (as I recall it was on the order of 3 seconds over the course of the 40k standard TT), but the primary improvements there were to braking and hubs. It was also unclear to which 404 Firecrest baseline the Firestrike's aerodynamic savings were: the 16 spoke original that we baseline, the then-current 18 spoke model, or the now-current 18 spoke with CX Sprint spokes, which the 404 Firecrest became coincident with the introduction of the 404 Firestrike. The ShowStopper brake surface and Cognition hubs were the primary stories at the Firestrike's launch. The 404 Firestrike is now apparently gone, replaced by the 404 NSW, the difference between the two being the hubs.
Price-wise, the 454 costs $4000 a set, the 404 NSW are $3000 a set, and the 404 Firecrest are $2000 a set. Cost is objective in that it is what it is, but it's also subjective in that for some people the $13k you might spend on a cutting edge superbike is a rounding error, while some people don't have those means.
The forums and comment boards have plenty of interesting posts about the goods and bads of these new wheels, but my take is pretty simple. For one, it's good that new ideas are coming out and that progress goes on. When we tested the 404 Firecrest, it was the laggard in cross wind stability, so improving that aspect is good business for Zipp and good for their users.
The other side is that I hope that road cyclists, and in particular people who might like to race, don't see all of this and say screw it, I have no interest in a sport that's that much of an arms race. You hear terms like "game changer" and other hyperbole, and it takes a lot of self-possession to know that the bike that you loved yesterday is still the same bike today even if the game has been "changed."
Our goal has always been to provide enthusiastic and committed riders with great gear at lower expense. The wheels we're sending out every day are aimed at bringing you joy when you use them, but also to match your specific goals and add a ton of style to your bike. We've always considered that the best comment someone can make when looking at one of our customer's bikes is "that guy/girl makes some great purchase choices."
Without data available to show for the 454, I can't say what stability gains they've made. Based on the data linked above, we can say that wheels in the "moderately deep for aluminum" category do exceptionally well in crosswinds. The world has also come to consensus (through data) that cycling actually takes place at low yaw angles, with somewhere around 80% of riding being done at equal to or less than 10* angle of incidence. Tour Magazine has even changed their weighting on this. From our iterative studies, we always knew this deep in our heads, but for us to try and influence the discussion on that comes off as unattractively Quixotic, so we just followed the prevalent conventions. Now the prevalent conventions have changed. Based on that, it's no challenge to make the statement that 80% of your road riding will take place at 10* wind angle or less, with the lower angles making up the majority even of that 80%. But if you take an even weighting of the wind tunnel data at 0, 2.5, 5, 7.5, and 10 degree and compare a Kinlin XC279 (which we continue to reference since it's representative of a lot of rims these days, and we have great data on it) to a 16 spoke 404 Firecrest, the time savings to the 404 is 14.2 seconds over the 40k 30mph TT (that's just comparing fronts - add half that again to account for the rear, so you're just a hair over 20 seconds for the set). My unshakeable belief is that your actual race, town line sprint race, Strava KOM hunting, and all other quantified riding pursuits are affected precisely bupkis by all of this. How the cost savings affect you is for you to decide.
We know that our stance on this often has all the sex appeal of a beige sweater vest, so I'll leave you with a pic of some wheels which aren't slowing anyone down, and have considerably more sex appeal than a beige sweater vest.