I think it's great that Burton has the time and money to come up with another good front light setup I must say I'm a big believer in not needing to re-invent the wheel or don't fix what aint broke. I use AYUPs on my bikes and think they are great (possibly better than Burton's lights) for the following reasons.
Cost. The basic AYUP kit is nearly 1/2 price of Burton's setup. $250
Equipment. You apear to get more equipment and features for your $ with AYUP. You get handlebar, helmet and headmount for the light, a mains charger as well as a car charger, an extension lead for the battery in case you want to put it in your jersey pocket or mount it somewhere else on the bike and also red caps for the lights in casr you want to use them as rear ones. The battery, though it is a dedicated one for AYUP and not AA or similar generic one, has a high and low beam function, flashing or steady and the latest 2012 batteries have "fuel gauge" built in that lets you know when they are getting low on charge. The standard battery is a (conservative) 3 hour one with a 6 hour one a $22 option.
Compact designand ease of portability. It's a 20 second job to transfer the lights between bikes. The lights are small and light for those road racer weight weenies and still allow mounting of other accessories such as bike computers or bells on the handlebars and stem.
Warranty.To some folks warranty is important. A bit tricky for non-Australian residents as I'm guessing most of you are as you will need to send them back to Oz if there is a problem, which I doubt you will have - I've had mine for about 4 years and they are working as well as the day I purchased them. No different to buying parts and accessories from UK retailers as a lot of us do.
An advantage Burton's lights may have over the AYUPs is they could be brighter, probably more impoprtant to a MTBer than a commuter or roadie.
Disclaimer: I have no connection to AYUP except being a happy customer. And, not dissing Burton's lights, just making what is meant to be an objective comparison.