Took some getting used to, but overall I am happy with the system so far.
Great instant depower
No fear of accidentally becoming unhooked
Chicken loop becomes "static" loop (great if your arms are getting tired)
Makes launching/landing/water relaunching/body dragging easier
Red ball on leash QR came off on second use (guess they have a replacement for these now)
Bar seems very far away (arms outstretched)
Accidentally triggered the QR to activate the leash when trying to grab the front lines to prevent luff
Not sure about adjustment strap not being necessary anymore (as advertised in UDS manual.) It seems like each rider is going to have his or her own comfortable place to hold the bar, which won't always translate into full power when you are hooked in. Hard to explain until you try it.
I am hoping that the future will bring some options for riders who want to shorten the harness line so the bar can be closer. On a regular chicken loop system you can adjust it, different riders have different needs. Seems like UDS needs to be adjustable too.
Actually launching-landing-bodydragging are harder because you cant steer the kite both ways with one hand due to no pivot point. Same for one handed jumps.De power is same as any bar because you can only depower a kite to a certin extent --more doesnt equal more depower.
I forgot to mention about the pivot steering.. it is a definite draw back. You can always hook in on long reaches if you want the old style back (though you don't have the depower capabilities of a regular chickenloop when you are hooked into UDS.)
However I still found certain aspects of launching and landing easier. I know that maui probably has worse case scenario of this since the launch at Kite Beach requires you to keep your kite moving (which would be pretty hard to do while running sideways with your board.)
However if you ever need to walk upwind and you don't need to keep the kite moving, then you have the advantage of being able to unhook and depower the kite significantly without pulling the depower strap. Depower is not any greater, but range of depower is improved significantly.
The pivot steering is quite hard to give up though, one reason I have not gotten rid of my old bar yet!
UDS is a dream come true for kite boarders that consistently use large kites, especially when riding in gusty conditions. Riders that use large kites tend to use a longer center line connected to the chicken loop. You just can't edge enough to handle the extra power caused by large gusts when you are flying a 20+ meter LEI. I can understand why the rider from Maui is not so thrilled about the UDS system. Most Maui riders generally fly smaller kites that require less depower (shorter line connected to the chicken loop) because you can edge the board and fly the kite forward in the window during a gust.
I think the benefits of UDS are marginal on LEI's that are 12M and smaller. However, on kites 16M and larger, UDS is a real breakthrough.