This is how it works, get Ultegra if you want great quality at a good price. Get Dura-Ace is you want great quality, with a bit more 'bling'. If you want lower maintenance, go Di2. If you like to tinker around, go mechanical.
Here's the Shimano sales pitch on the two:
Shimano Ultegra sits one below the professional-level Dura-Ace.
This 11-speed group has many of the same design features as the range topping Dura-Ace and offers all the performance most riders will ever need, but is slightly heavier than Dura-Ace.
Like Dura-Ace, Ultegra includes both Di2 electronic shifting and hydraulic disc options in addition to traditional mechanical shifting and rim brakes.
Dura-Ace is the pinnacle of Shimano's range and features on many top-level pro machines. It offers 11-speed gearing and combines top-end design with lightweight materials such as high-grade alloys, carbon fibre and titanium.