I had 2 of these on backorder for a few months and Zipp must have finally received a batch because they started showing up in inventory on the web a couple weeks ago - same time I got mine in the mail.
Installed one pair on one of my bikes but because the bar's internal cable routing requires a complete brake and shifter cable swap, I have not managed to get the second bar installed. But I've put about 150 miles on the bars so far, and these are my thoughts:
* Internal cable routing is cool, but means installation take a little more time than with a "normal" bar.
* My favorite all time bar for comfort/shape is the FSA K-Wing carbon (same shape is also used in the FSA Plasma integrated bar/stem). The FSA bars, however, are too flexy for me, which is why I decided to make the switch. The Vuka Sprint's have a similar "ergo" drop section, which I like, but the FSAs are more comfortable on the tops. Why? Because the FSAs have a pretty round trailing edge, while the Zipps have a fairly sharp trailing edge, which can dig into your palm. If you try to ride the Zipps on the tops with your hand wrapped around and your thumbs under the tops (the most secure grip), these bars are not going to be comfortable for you. But if you ride (1) with your thumbs on top, (2) with your thumbs parallel to the ground right along the trailing edge of the tops or (3) grab the tops right near the stem in a very narrow grip, it's fine. I don't ride a lot in the tops, and when I do it is really just to vary hand/body position, so this doesn't bother me. But if you ride a lot in the tops in a full grip with your thumbs under the bar, I don't think you'll like this bar. I should also mention that I did not tape the tops of my Zipps, but the trailing edge on the Zipp's tops is so sharp that I don't think bar tape would change my assessment much, if at all. The FSA tops I never taped either and they were crazy comfortable (at least for me) that way.
* Used with a Zipp SC SL stem, there is just enough round section in the middle of the bars to mount a relatively "thin" bar-mounted accessory on either side of the stem. For me, this means my BarFly mount fits nicely just to the right of the stem's clamp and I can mount a K-Edge GoPro mount on the left side of the clamp when I want to video.
* I find the Zipps to be nice and stiff - much better than the FSAs.
* They definitely look cool on the bike, without being too over-the-top. As far as quantifiable aero advantage, I'll leave that one alone. But it's hard to see how they can't be as good if not better than a standard round bar. Hard to see how they could be worse.
* I mounted my Red brifters at almost the very top of the Zipp-marked clamping area. This gave me a pretty-much flat transition between the bar and the brifter's hook top, which is what I prefer. Also, mounted in this position, the Red brifters sync up very well with the internal cable routing holes in the Zipps.
Overall, I am very happy with the Vuka Sprints and just have to find a little time to get the other pair on my second bike.
EVO Hi-Mod | 9070 di2 | Pioneer PM | Enve 3.4s/6.7s
SuperX Hi-Mod Disc | Sram Red | Pioneer PM | Zipp 303s
P5 | 9070 di2 | ENVE SES | Pioneer PM | Zipp 808/Super 9 Disc
T1 | Scatto | Rolf Prima FX58/Zipp Super 9 Disc