This 11-30T cassette can be found on the 11 speed road groupsets, which are the Dura-Ace, Ultegra and 105 series. The gear ratios are exactly the same (11,12,13,14,15,17,19,21,24,27,30), as first seen on the Canyon Endurace. Differences are the material used, the construction, the weight, the surface treatment and of course the price.
Let's compare the Dura-Ace R9100 cassette with the Ultegra R8000 cassette, both of which are the 11-30T variety. Why does the Dura-Ace cassette cost twice as much as Ultegra cassette? Is it purely due to the use of the titanium sprockets in the Dura-Ace cassette?
R9100 - Dura-Ace R9100 cassette
R8000 - Ultegra R8000 cassette
R9100 has the largest two titanium sprockets (27T and 30T) mounted together on an aluminium spider
Weighs only 64 grams for these two sprockets, due to the use of the lightweight aluminium spider and the titanium sprockets.
Next 3 sprockets in the R9100 (19T, 21T, 24T) are also made of titanium, and are riveted to a carbon fibre spider.
Very lightweight due to the 3 titanium sprockets and the carbon fibre spider used in R9100.
As you can see, the Dura-Ace R9100 cassette has spared no expense to make sure it is as lightweight as possible, through the use of titanium for its 5 largest sprockets and the use of aluminium and carbon fibre spiders. Using titanium in the smaller sprockets (17T and below) will probably result in minimal weight savings at a much higher cost.
On the other hand, as the Ultegra R8000 is more cost sensitive, it will have to use a different construction and material to achieve a lower cost.
R8000 has the 3 largest sprockets (24T, 27T, 30T) mounted together on an aluminium spider
Weighs 135 grams for these three steel sprockets plus spider. Cannot compare directly to the Dura-Ace cassette as the number of sprockets mounted on the last spider is different.
R8000 has the 19T and 21T steel sprockets mounted together, on a carbon fibre spider
Weighs 49 grams for these two steel sprockets on the carbon fibre spider
At this point, we can compare the sub units of the R9100 vs the R8000, just for the last 5 sprockets.
(27T & 30T) + (19T & 21T & 24T) = 64g + 59g = 123 grams
(24T & 27T & 30T) + (19T + 21T) = 135g + 49g = 184 grams
For the last 5 sprockets alone, the weight difference is already 61 grams. The remaining 6 sprockets are mounted individually and are made of steel, so the weight should be similar regardless of Dura-Ace or Ultegra.
Weight of whole R9100 11-30T cassette is only 206 grams
Weight of whole R8000 11-30T cassette is 270 grams
If you compare the weight difference for the whole cassette, the Dura-Ace cassette is lighter than the Ultegra cassette by 64 grams, out of which 61 grams comes from the last 5 sprockets.
In other words, almost all of the weight difference between the R9100 and the R8000 11-30T cassettes come from the last 5 titanium sprockets!
If you are a weight weenie, you can save 64 grams from the cassette by choosing a Dura-Ace R9100 vs Ultegra R8000. However, if this weight difference does not matter to you, you can save quite a bit of money by using the Ultegra cassette which shifts just as well.